Itwouldbewellifobservationsweresodirectedastoascertain，atleastuptotenortwenty，theincrease[ofinterval]requiredbyeachadditionalclickinaseriesforthesenseofdiscontinuitytoremainconstantthroughout。"[14]
[p。615]Wherethefirstimpressionfallsononesense，andthesecondonanother，theperceptionoftheinterveningtimetendstobelesscertainanddelicate，anditmakesadifferencewhichimpressioncomesfirst。Thus，Exnerfound[15]thesmallestperceptibleintervaltobe，inseconds:Fromsighttotouch……0。071
Fromtouchtosight……0。053
Fromsighttohearing……0。16
Fromhearingtosight……0。06
Fromoneeartoanother……0。064Tobeconsciousofatimeintervalatallisonething；totellwhetheritbeshorterorlongerthananotherintervalisadifferentthing。
Anumberofexperimentaldataareonhandwhichgiveusameasureofthedelicacyofthislatterperception。Theproblemisthatofthesmallestdifferencebetweentwotimeswhichwecanperceive。
Thedifferenceisatitsminimumwhenthetimesthemselvesareveryshort。Exner，[16]reactingasrapidlyaspossiblewithhisfoot，uponasignalseenbytheeyespark，notedallthereactionswhichseemedtohimeithersloworfastinthemaking。Hethoughtthusthatdeviationsofabout1/100ofasecondeitherwayfromtheaveragewere[p。616]correctlynoticedbyhimatthetime。Theaveragewashere0。1840"。HallandJastrowlistenedtotheintervalsbetweentheclicksoftheirapparatus。Betweentwosuchequalintervalsof4。27"each，amiddleintervalwasincluded，whichmightbemadeeithershorterorlongerthantheextremes。"Aftertheserieshadbeenheardtwooreventhreetimes，noimpressionoftherelativelengthofthemiddleintervalwouldoftenexist，andonlyafterhearingthefourthandlast[repetitionoftheseries]wouldthejudgmentinclinetotheplusorminusside。Insertingthevariablebetweentwoinvariableandlikeintervalsgreatlyfacilitatedjudgment，whichbetweentwounliketermsisfarlessaccurate。"[17]Threeobserversintheseexperimentsmadenoerrorwhenthemiddleintervalvaried1/60
fromtheextremes。Whenitvaried1/120，errorsoccurred，butwerefew，Thiswouldmaketheminimumabsolutedifferenceperceivedaslargeas0。355。"
Thisminimumabsolutedifference，ofcourse，increasesasthetimescomparedgrowlong。Attemptshavebeenmadetoascertainwhatratioitbearstothetimesthemselves。AccordingtoFechner’s’PsychophysicLaw’itoughtalwaystobearthesameratio。Variousobservers，however，havefoundthisnottobethecase。[18]Onthecontrary，veryinterestingoscillationsintheaccuracyofjudgmentandinthedirectionoftheerror——oscillationsdependentupontheabsoluteamountofthetimescompared——havebeennoticedbyallwhohaveexperimentedwiththequestion。
Oftheseabriefaccountmaybegiven。
Inthefirstplace，ineverylistofintervalsexperimentedwiththerewillbefoundwhatVierordtcallsan’INDIFFERENCE-POINT；’thatistosay，anintervalwhichwejudgewithmaximumaccuracy，atimewhichwetendtoestimateasneitherlongerorshorterthanitreallyis，andawayfromwhich，[p。617]inbothdirections，errorsincreasetheirsize。[19]
Thistimevariesfromoneobservertoanother，butitsaverageisremarkablyconstant，asthefollowingtableshows。[20]
Thetimes，notedbytheear，andtheaverageindifference-pointsgiveninsecondswere，for——Wundt[21]……0。72
Kollert[22]……0。75
Estelprobably……0。75
Mehner……0。71
Stevens[23]……0。71
Mach[24]……0。35
Buccolaabout[25]……0。40Theoddthingaboutthesefiguresistherecurrencetheyshowinsomanymenofaboutthreefourthsofasecond，[p。618]astheintervaloftimemosteasytocatchandreproduce。Odderstill，bothEstelandMehnerfoundthatmultiplesofthistimeweremoreaccuratelyreproducedthanthetime-intervalsofintermediarylength；[26]andGlassfoundacertainperiodicity，withtheconstantincrementof1。25sec。，inhisobservations。
Therewouldseemthustoexistsomethinglikeaperiodicorrhythmicsharpeningofourtime-sense，ofwhichtheperioddifferssomewhatfromoneobservertothenext。
Oursenseoftime，likeothersenses，seemssubjecttothelawofcontrast。ItappearedprettyplainlyinEstel’sobservationsthatanintervalsoundedshorterifalongonehadimmediatelyprecededit，andlongerwhentheoppositewasthecase。
Likeothersenses，too，oursenseoftimeissharpenedbypractice。
Mehnerascribesalmostallthediscrepanciesbetweenotherobserversandhimselftothiscausealone。[27]
Tracksoftimefilledwithclicksofsoundseemlongerthanvacantonesofthesameduration，whenthelatterdoesnotexceedasecondortwo。[28]This，whichremindsoneofwhathappenswithspacesseenbytheeye，becomesreversedwhenlongertimesaretaken。Itis，perhaps，inaccordancewiththislawthataloudsound，limitingashortintervaloftime，makesitappearlonger，aslightsoundshorter。
Incomparingintervalsmarkedoutbysounds，wemusttakecaretokeepthesoundsuniform。[29]
Thereisacertainemotionalfeelingaccompanyingtheintervalsoftime，asiswellknowninmusic。Thesenseofhastegoeswithonemeasureofrapidity，thatofdelaywithanother；andthesetwofeelingsharmonizewithdifferentmentalmoods。Vierordtlistenedtoseriesofstrokesperformedbyametronomeatratesvaryingfrom40to200a[p。
619]minute，andfoundthattheyverynaturallyfellintosevencategories，from’veryslow’to’veryfast。’[30]Eachcategoryoffeelingincludedtheintervalsfollowingeachotherwithinacertainrangeofspeed，andnoothers。Thisisaqualitative，notaquantitativejudgment——anæ；stheticjudgment，infact。Themiddlecategory，ofspeedthatwasneutral，or，ashecallsit，’adequate，’containedintervalsthatweregroupedabout0。62second，andVierordtsaysthatthismadewhatonemightalmostcallanagreeabletime。[31]
Thefeelingoftimeandaccentinmusic，ofrhythm，isquiteindependentofthatofmelody。Tuneswithmarkedrhythmcanbereadilyrecognizedwhensimplydrummedonthetablewiththefinger-tips。WEHAVENOSENSEFOREMPTYTIME。
Althoughsubdividingthetimebybeatsofsensationaidsouraccurateknowledgeoftheamountofitthatelapses，suchsubdivisiondoesnotseematthefirstglanceessentialtoourperceptionofitsflow。Letonesitwithclosedeyesand，abstractingentirelyfromtheouterworld，attendexclusivelytothepassageoftime，likeonewhowakes，asthepoetsays，"toheartimeflowinginthemiddleofthenight，andallthingsmovingtoadayofdoom。"Thereseemsundersuchcircumstancesasthesenovarietyinthematerialcontentofourthought，andwhatwenoticeappears，ifanything，tobethepureseriesofdurationsbudding，asitwere，andgrowingbeneathourindrawngaze。Isthisreallysoornot？Thequestionisimportant，for，iftheexperiencebewhatitroughlyseems，wehaveasortofspecialsenseforpuretime——asensetowhichemptydurationisanadequatestimulus；
whileifitbeanillusion，itmustbethatourperceptionoftime’sflight，intheexperiencesquoted，isduetothefillingofthetime，andtoourmemoryofacontentwhichithadamomentprevious，andwhichwefeeltoagreeordisagreewithitscontentnow。
Ittakesbutasmallexertionofintrospectiontoshow[p。620]thatthelatteralternativeisthetrueone，andthatwecannomoreintuitadurationthanwecanintuitanextension，devoidofallsensiblecontent。Justaswithclosedeyesweperceiveadarkvisualfieldinwhichacurdlingplayofobscurestluminosityisalwaysgoingon；so，beweneversoabstractedfromdistinctoutwardimpressions，wearealwaysinwardlyimmersedinwhatWundthassomewherecalledthetwilightofourgeneralconsciousness。Ourheart-beats，ourbreathing，thepulsesofourattention，fragmentsofwordsorsentencesthatpassthroughourimagination，arewhatpeoplethisdimhabitat。Now，alltheseprocessesarerhythmical，andareapprehendedbyus，astheyoccur，intheirtotality；thebreathingandpulsesofattention，ascoherentsuccessions，eachwithitsriseandfall；theheart-beatssimilarly，onlyrelativelyfarmorebrief；thewordsnotseparately，butinconnectedgroups。Inshort，emptyourmindsaswemay，someformofchangingprocessremainsforustofeel，andcannotbeexpelled。Andalongwiththesenseoftheprocessanditsrhythmgoesthesenseofthelengthoftimeitlasts。Awarenessofchangeisthustheconditiononwhichourperceptionoftime’sflowdepends；butthereexistsnoreasontosupposethatemptytime’sownchangesaresufficientfortheawarenessofchangetobearoused。Thechangemustbeofsomeconcretesort——anoutwardorinwardsensibleseries，oraprocessofattentionorvolition。[32]
[p。621]Andhereagainwehaveananalogywithspace。Theearliestformofdistinctspace-perceptionisundoubtedlythatofamovementoversomeoneofoursensitivesurfaces，andthismovementisoriginallygivenasasimplewholeoffeeling，andisonlydecomposedintoitselements——successivepositionssuccessivelyoccupiedbythemovingbody——whenoureducationindiscriminationismuchadvanced。[p。622]Butamovementisachange，aprocess；soweseethatinthetime-worldandthespace-worldalikethefirstknownthingsarenotelements，butcombinations，notseparateunits，butwholesalreadyformed。Theconditionofbeingofthewholesmaybetheelements；buttheconditionofourknowingtheelementsisourhavingalreadyfeltthewholesaswholes。
Intheexperienceofwatchingemptytimeflow——’empty’tobetakenhereafterintherelativesensejustsetforth——wetellitoffinpulses。
Wesay’now！now！now！’orwecount’more！more！more！’aswefeelitbud。
Thiscompositionoutofunitsofdurationiscalledthelawoftime’sdiscreteflow。Thediscretenessis，however，merelyduetothefactthatoursuccessiveactsofrecognitionorapperceptionofwhatitisarediscrete。Thesensationisascontinuousasanysensationcanbe。Allcontinuoussensationsarenamedinbeats。Wenoticethatacertainfinite’more’ofthemispassingoralreadypast。ToadoptHodgson’simage，thesensationisthemeasuring-tape，theperceptionthedividing-enginewhichstampsitslength。Aswelistentoasteadysound，wetakeitinindiscretepulsesofrecognition，callingitsuccessively’thesame！thesame！thesame！’Thecasestandsnootherwisewithtime。
Afterasmallnumberofbeatsourimpressionoftheamountwehavetoldoffbecomesquitevague。Ouronlywayofknowingitaccuratelyisbycounting，ornoticingtheclock，orthroughsomeothersymbolicconception。[33]Whenthetimesexceedhoursordays，theconceptionisabsolutelysymbolic。
Wethinkoftheamountwemeaneithersolelyasaname，orbyrunningoverafewsalientdatestherein，withnopretenceofimaginingthefulldurationsthatliebetweenthem。Noonehasanythinglikeaperceptionofthegreaterlengthofthetimebetweennowandthefirstcenturythanofthatbetweennowandthetenth。Toanhistorian，[p。623]itistrue，thelongerintervalwillsuggestahostofadditionaldatesandevents，andsoappearamoremultitudinousthing。Andforthesamereasonmostpeoplewillthinktheydirectlyperceivethelengthofthepastfortnighttoexceedthatofthepastweek。Butthereisproperlynocomparativetimeintuitioninthesecasesatall。Itisbutdatesandevents，representingtime；theirabundancesymbolizingitslength。Iamsurethatthisisso，evenwherethetimescomparedarenomorethananhourorsoinlength。ItisthesamewithSpacesofmanymiles，whichwealwayscomparewitheachotherbythenumberswhichmeasurethem。[34]
[p。624]Fromthiswepassnaturallytospeakofcertainfamiliarvariationsinourestimationoflengthsoftime。Ingeneral，atimefilledwithvariedandinterestingexperiencesseemsshortinpassing，butlongaswelookback。Ontheotherhand，atractoftimeemptyofexperiencesseemslonginpassing，butinretrospectshort。Aweekoftravelandsight-seeingmaysubtendananglemorelikethreeweeksinthememory；
andamonthofsicknesshardlyyieldsmorememoriesthanaday。Thelengthinretrospectdependsobviouslyonthemultitudinousnessofthememorieswhichthetimeaffords。Manyobjects，events，changes，manysubdivisions，immediatelywidentheviewaswelookback。Emptiness，monotony，familiarity，makeitshrivelup。InVonHoltei’s’Vagabonds’oneAntonisdescribedasrevisitinghisnativevillage。
"Sevenyears，"heexclaims，"sevenyearssinceIranaway！Morelikeseventyitseems，somuchhashappened。Icannotthinkofitallwithoutbecomingdizzy——atanyratenotnow。Andyetagain，whenIlookatthevillage，atthechurch-tower，itseemsasifIcouldhardlyhavebeensevendaysaway。"
Prof。Lazarus[35]fromwhomIborrowthisquotation，thusexplainsbothofthesecontrastedillusionsbyourprincipleoftheawakenedmemoriesbeingmultitudinousorfew:
"Thecircleofexperiences，widelyextended，richinvariety，whichhehadinviewonthedayofhisleavingthevillagerisesnowinhismindasitsimageliesbeforehim。Andwithit——inrapidsuccessionandviolentmotion，notinchronologicorder，orfromchronologicmotives，butsuggestingeachotherbyallsortsofconnections——arisemassiveimagesofallhisrichvagabondageandrovinglife。Theyrollandwaveconfusedlytogether，firstperhapsonefromthefirstyear，thenfromthesixth，soonfromthesecond，againfromthefifth，the[p。625]first，etc。，untilitseemsasifseventyyearsmusthavebeenthere，andhereelswiththefulnessofhisvision……Thentheinnereyeturnsawayfromallthispast。
Theouteroneturnstothevillage，especiallytothechurch-tower。Thesightofitcallsbacktheoldsightofit，sothattheconsciousnessisfilledwiththatalone，oralmostalone。Theonevisioncomparesitselfwiththeother，andlookssonear，sounchanged，thatitseemsasifonlyaweekoftimecouldhavecomebetween。"
Thesamespaceoftimeseemsshorteraswegrowolder——thatis，thedays，themonths，andtheyearsdoso；whetherthehoursdosoisdoubtful，andtheminutesandsecondstoallappearanceremainaboutthesame。
"Whoevercountsmanylustrainhismemoryneedonlyquestionhimselftofindthatthelastofthese，thepastfiveyears，havespedmuchmorequicklythantheprecedingperiodsofequalamount。Letanyonerememberhislasteightortenschoolyears:itisthespaceofacentury。Comparewiththemthelasteightortenyearsoflife:itisthespaceofanhour。"
SowritesProf。PaulJanet，[36]andgivesasolutionwhichcanhardlybesaidtodiminishthemystery。Thereisalaw，hesays，bywhichtheapparentlengthofanintervalatagivenepochofaman’slifeisproportionaltothetotallengthofthelifeitself。Achildof10feelsayearas1/10
ofhiswholelife——amanof50as1/50，thewholelifemeanwhileapparentlypreservingaconstantlength。Thisformularoughlyexpressesthephenomena，itistrue，butcannotpossiblybeanelementarypsychiclaw；anditiscertainthat，ingreatpartatleast，theforeshorteningoftheyearsaswegrowolderisduetothemonotonyofmemory’scontent，andtheconsequentsimplificationofthebackward-glancingview。Inyouthwemayhaveanabsolutelynewexperience，subjectiveorobjective，everyhouroftheday。Apprehensionisvivid，retentivenessstrong，andourrecollectionsofthattime，likethoseofatimespentinrapidandinterestingtravel，areofsomethingintricate，multitudinous，andlong-drawn-out。Butaseachpassingyearconvertssomeofthisexperienceintoautomaticroutinewhichwehardlynoteatall，thedaysandtheweekssmooththemselvesoutinrecollectiontocontentlessunits，andtheyearsgrowhollowandcollapse。
[p。626]Somuchfortheapparentshorteningoftractsoftimeinretrospect。
Theyshorteninpassingwheneverwearesofullyoccupiedwiththeircontentasnottonotetheactualtimeitself。Adayfullofexcitement，withnopause，issaidtopass’ereweknowit。’Onthecontrary，adayfullofwaiting，ofunsatisfieddesireforchange，willseemasmalleternity。Tæ；dium，ennui，Langweile，boredom，arewordsforwhich，probably，everylanguageknowntomanhasitsequivalent。
Itcomesaboutwhenever，fromtherelativeemptinessofcontentofatractoftime，wegrowattentivetothepassageofthetimeitself。Expecting，andbeingreadyfor，anewimpressiontosucceed；whenitfailstocome，wegetanemptytimeinsteadofit；andsuchexperiences，ceaselesslyrenewed，makeusmostformidablyawareoftheextentofthemeretimeitself。[37]
Closeyoureyesandsimplywaittohearsomebodytellyouthataminutehaselapsed。Thefulllengthofyourleisurewithitseemsincredible。
Youengulfyourselfintoitsbowelsasintothoseofthatinterminablefirstweekofanoceanvoyage，andfindyourselfwonderingthathistorycanhaveovercomemanysuchperiodsinitscourse。Allbecauseyouattendsocloselytothemerefeelingofthetimeperse，andbecauseyourattentiontothatissusceptibleofsuchfine-grainedsuccessivesubdivision。
Theodiousnessofthewholeexperiencecomesfromitsinsipidity；
forstimulationistheindispensablerequisiteforpleasureinanexperience，andthefeelingofbaretimeistheleaststimulatingexperiencewecanhave。[38]Thesensationoftæ；diumisaprotest，saysVolkmann，againsttheentirepresent。
[p。627]Exactlyparallelvariationsoccurinourconsciousnessofspace。
Aroadwewalkbackover，hopingtofindateachstepanobjectwehavedropped，seemstouslongerthanwhenwewalkedoverittheotherway。
Aspacewemeasurebypacingappearslongerthanonewetraversewithnothoughtofitslength。Andingeneralanamountofspaceattendedtoinitselfleaveswithusmoreimpressionofspaciousnessthanoneofwhichweonlynotethecontent。[39]
Idonotsaythateverythinginthesefluctuationsofestimatecanbeaccountedforbythetime’scontentbeingcrowdedandinteresting，orsimpleandtame。Bothintheshorteningoftimebyoldageandinitslengtheningbyennuisomedeepercausemaybeatwork。Thiscausecanonlybeascertained，ifitexist，byfindingoutwhyweperceivetimeatall。Tothisinquiryletus，thoughwithoutmuchhope，proceed。THEFEELINGOFPASTTIMEISAPRESENTFEELING。
Ifaskedwhyweperceivethelightofthesun，orthesoundofanexplosion，wereply，"Becausecertainouterforces，ether-wavesorair-waves，smiteuponthebrain，awakeningthereinchanges，towhichtheconsciousperceptions，lightandsound，respond。"Butwehastentoaddthatneitherlightnorsoundcopyormirrortheether-orair-waves；theyrepresentthemonlysymbolically。Theonlycase，saysHelmholtz，inwhichsuchcopyingoccurs，andinwhich[p。628]
"ourperceptionscantrulycorrespondwithouterreality，isthatofthetime-successionofphenomena。Simultaneity，succession，andtheregularreturnofsimultaneityorsuccession，canobtainaswellinsensationsasinouterevents。Events，likeourperceptionsofthem，takeplaceintime，sothatthetime-relationsofthelattercanfurnishatruecopyofthoseoftheformer。Thesensationofthethunderfollowsthesensationofthelightningjustasthesonorousconvulsingoftheairbytheelectricdischargereachestheobserver’splacelaterthanthatoftheluminiferousether。"[40]
Oneexperiencesanalmostinstinctiveimpulse，inpursuingsuchreflectionsasthese，tofollowthemtoasortofcrudespeculativeconclusion，andtothinkthathehasatlastgotthemysteryofcognitionwhere，touseavulgarphrase，’thewoolisshort。’Whatmorenatural，wesay，thanthatthesequencesanddurationsofthingsshouldbecomeknown？Thesuccessionoftheouterforcesstampsitselfasalikesuccessionuponthebrain。
Thebrain’ssuccessivechangesarecopiedexactlybycorrespondinglysuccessivepulsesofthementalstream。Thementalstream，feelingitself，mustfeelthetime-relationsofitsownstates。Butasthesearecopiesoftheoutwardtime-relations，somustitknowthemtoo。Thatistosay，theselattertime-relationsarousetheirowncognition；or，inotherwords，themereexistenceoftimeinthosechangesoutofthemindwhichaffectthemindisasufficientcausewhytimeisperceivedbythemind。
Thisphilosophyisunfortunatelytoocrude。Eventhoughweweretoconceivetheoutersuccessionsasforcesstampingtheirimageonthebrain，andthebrain’ssuccessionsasforcesstampingtheirimageonthemind，[41]still，betweenthemind’sownchangesbeingsuccessive，andknowingtheirownsuccession，liesasbroadachasmasbetweentheobjectandsubjectofanycaseofcognitionintheworld。Asuccessionoffeelings，inandofitself，isnotafeelingofsuccession。Andsince，tooursuccessivefeelings，afeelingoftheirownsuccessionisadded，thatmustbetreatedasan[p。629]additionalfactrequiringitsownspecialelucidation，whichthistalkaboutoutertime-relationsstampingcopiesofthemselveswithin，leavesalluntouched。
Ihaveshown，attheoutsetofthearticle，thatwhatispast，tobeknownaspast，mustbeknownwithwhatispresent，andduringthe’present’spotoftime。Astheclearunderstandingofthispointhassomeimportance，letme，attheriskofrepetition，recurtoitagain。
Volkmannhasexpressedthematteradmirably，asfollows:
"Onemightbetemptedtoanswerthequestionoftheoriginofthetime-ideabysimplypointingtothetrainofideas，whosevariousmembers，startingfromthefirst，successivelyattaintofullclearness。Butagainstthisitmustbeobjectedthatthesuccessiveideasarenotyettheideaofsuccession，becausesuccessioninthoughtisnotthethoughtofsuccession。
IfideaAfollowsideaB，consciousnesssimplyexchangesoneforanother。
ThatBcomesafterAisforourconsciousnessanon-existentfact；
forthisafterisgivenneitherinBnorinA；andnothirdideahasbeensupposed。ThethinkingofthesequenceofBuponAisanotherkindofthinkingfromthatwhichbroughtforthAandthenbroughtforthB；andthisfirstkindofthinkingisabsentsolongasmerelythethinkingofAandthethinkingofBarethere。Inshort，whenwelookatthemattersharply，wecometothisantithesis，thatifAandBaretoberepresentedasoccurringinsuccessiontheymustbesimultaneouslyrepresented；
ifwearetothinkofthemasoneaftertheother，wemustthinkthembothatonce。"[42]
Ifwerepresenttheactualtime-streamofourthinkingbyanhorizontalline，thethoughtofthestreamorofanysegmentofitslength，past，present，ortocome，mightbefiguredinaperpendicularraiseduponthehorizontalatacertainpoint。Thelengthofthisperpendicularstandsforacertainobjectorcontent，whichinthiscaseisthetimethoughtof，andallofwhichisthoughtoftogetherattheactualmomentofthestreamuponwhichtheperpendicularisraised。Mr。JamesWardputsthematterverywellinhismasterlyarticle’Psychology’inthenintheditionoftheEncyclopæ；diaBritannica，page64。Hesays:
"Wemay，ifwerepresentsuccessionasaline，representsimultaneityasasecondlineatrightanglestothefirst；emptytime——ortime-lengthwithouttime-breadth，wemaysay——isamereabstraction。Now，itiswiththeformerlinethatwehavetodointreatingoftime[p。630]asitis，andwiththelatterintreatingofourintuitionoftime，where，justasinaperspectiverepresentationofdistance，weareconfinedtolinesinaplaneatrightanglestotheactuallineofdepth。Inasuccessionofevents，sayofsense-impressions，ABCDE……，thepresenceofBmeanstheabsenceofAandC，butthepresentationofthissuccessioninvolvesthesimultaneouspresenceinsomemodeorotheroftwoormoreofthepresentationsABCD。Inreality，past，present，andfuturearedifferencesintime，butinpresentationallthatcorrespondstothesedifferencesisinconsciousnesssimultaneously。"
Thereisthusasortofperspectiveprojectionofpastobjectsuponpresentconsciousness，similartothatofwidelandscapesuponacamera-screen。
Andsincewesawawhileagothatourmaximumdistinctintuitionofdurationhardlycoversmorethanadozensecondswhileourmaximumvagueintuitionisprobablynotmorethanthatofaminuteorso，wemustsupposethatthisamountofdurationispicturedfairlysteadilyineachpassinginstantofconsciousnessbyvirtueofsomefairlyconstantfeatureinthebrain-processtowhichtheconsciousnessistied。Thisfeatureofthebrain-process，whateveritbe，mustbethecauseofourperceivingthefactoftimeatall。[43]Thedurationthussteadilyperceivedishardlymorethanthe’speciouspresent，’asitwascalledafewpagesback。Itscontentisinaconstantflux，eventsdawningintoitsforwardendasfastastheyfadeoutofitsrearwardone，andeachofthemchangingitstime-coefficientfrom’notyet，’or’notquiteyet，’to’justgone’or’gone，’asitpassesby。Meanwhile，thespeciouspresent，theintuitedduration，standspermanent，liketherainbowonthewaterfall，withitsownqualityunchangedbytheeventsthatstreamthroughit。Eachofthese，asitslipsout，retainsthepowerofbeingreproduced；
andwhenreproduced，isreproducedwiththedurationandneighborswhichitoriginallyhad。Pleaseobserve，however，thatthereproductionofanevent，afterithasoncecompletelydroppedoutoftherearwardendofthespeciouspresent，isanentirelydifferentpsychicfactfromitsdirectperceptioninthespeciouspresentasathingimmediatelypast。
Acreaturemightbeentirelydevoidofreproductivememory，andyethavethetime-sense；butthe[p。631]latterwouldbelimited，inhiscase，tothefewsecondsimmediatelypassingby。Timeolderthanthathewouldneverrecall。Iassumereproductioninthetext，becauseIamspeakingofhumanbeingswhonotoriouslypossessit。Thusmemorygetsstrewnwithdatedthings——datedinthesenseofbeingbeforeoraftereachother。[44]Thedateofathingisamererelationofbeforeorafterthepresentthingorsomepastorfuturething。Somethingswedatesimplybymentallytossingthemintothepastorfuturedirection。
SoinspacewethinkofEnglandassimplytotheeastward，ofCharlestonaslyingsouth。But，again，wemaydateaneventexactly，byfittingitbetweentwotermsofapastorfutureseriesexplicitlyconceived，justaswemayaccuratelythinkofEnglandorCharlestonbeingjustsomanymilesaway。[45]
Thethingsandeventsthusvaguelyorexactlydatedbecomethenceforwardthosesignsandsymbolsoflongertime-spaces，ofwhichwepreviouslyspoke。
Accordingaswethinkofamultitudeofthem，oroffew，soweimaginethetimetheyrepresenttobelongorshort。Buttheoriginalparagonandprototypeofallconceivedtimesisthespeciouspresent，theshortdurationofwhichweareimmediatelyandincessantlysensible。[p。632]TOWHATCEREBRALPROCESSISTHESENSEOFTIMEDUE？
Now，towhatelementinthebrain-processmaythissensibilitybedue？Itcannot，aswehaveseen，beduetothemeredurationitselfoftheprocess；itmustbeduetoanelementpresentateverymomentoftheprocess，andthiselementmustbearthesameinscrutablesortofrelationtoitscorrelativefeelingwhichallotherelementsofneuralactivitybeartotheirpsychicproducts，bethelatterwhattheymay。Severalsuggestionshavebeenmadeastowhattheelementisinthecaseoftime。
Treatingoftheminanote，[46]Iwilltrytoexpressbrieflytheonlyconclusionwhich[p。633]seemstoemergefromastudyofthemandofthefacts——unripethoughthatconclusionbe。
[p。634]Thephenomenaof’summationofstimuli’inthenervoussystemprovethateachstimulusleavessomelatentactivity[p。635]behinditwhichonlygraduallypassesaway。Seeabove，pp。82-85。Psychologicalproofofthesamefactisaffordedbythose’after-images’whichweperceivewhenasensorialstimulusisgone。Wemayreadoffpeculiaritiesinanafter-image，leftbyanobjectontheeye，whichwefailedtonoteintheoriginal。Wemay’harkback’andtakeinthemeaningofasoundseveralsecondsafterithasceased。Delayforaminute，however，andtheechoitselfoftheclockorthequestionismute；presentsensationshavebanisheditbeyondrecall。Withthefeelingofthepresentthingtheremustatalltimesminglethefadingechoofallthoseotherthingswhichthepreviousfewsecondshavesupplied。Or，tostateitinneuralterms，thereisateverymomentacumulationofbrain-processesoverlappingeachother，ofwhichthefainteronesarethedyingphasesofprocesseswhichbutshortlypreviouswereactiveinamaximaldegree。TheAMOUNTOFTHEOVERLAPPINGdeterminesthefeelingoftheDURATIONOCCUPIED。WHATEVENTSshallappeartooccupythedurationdependsonjustWHATPROCESSEStheoverlappingprocessesare。Weknowsolittleoftheintimatenatureofthebrain’sactivitythatevenwhereasensationmonotonouslyendures，wecannotsaythattheearliermomentsofitdo[p。636]notleavefadingprocessesbehindwhichcoexistwiththoseofthepresentmoment。Durationandeventstogetherformourintuitionofthespeciouspresentwithitscontent。[47]Whysuchanintuitionshouldresultfromsuchacombinationofbrain-processesIdonotpretendtosay。AllIaimatistostatethemostelementalformofthepsycho-physicalconjunction。
Ihaveassumedthatthebrain-processesaresensationalones。ProcessesofactiveattentionseeMr。Ward’saccountinthelongfoot-notewillleavesimilarfadingbrain-processesbehind。Ifthementalprocessesareconceptual，acomplicationisintroducedofwhichIwillinamomentspeak。
Meanwhile，stillspeakingofsensationalprocesses，aremarkofWundt’swillthrowadditionallightontheaccountIgive。Asisknown，Wundtandothershaveprovedthateveryactofperceptionofasensorialstimulustakesanappreciabletime。Whentwodifferentstimuli——e。g。asightandasound——aregivenatonceornearlyatonce，wehavedifficultyinattendingtoboth，andmaywronglyjudgetheirinterval，oreveninverttheirorder。
Now，astheresultofhisexperimentsonsuchstimuli，Wundtlaysdownthislaw:[48]thatofthethreepossibledeterminationswemaymakeoftheirorder——
"namely，simultaneity，continuoustransition，anddiscontinuoustransition——onlythefirstandlastarerealized，neverthesecond。Invariably，whenwefailtoperceivetheimpressionsassimultaneous，wenoticeashorterorlongeremptytimebetweenthem，whichseemstocorrespondtothesinkingofoneoftheideasandtotheriseoftheother……Forourattentionmayshareitselfequallybetweenthetwoimpressions，whichwillthencomposeonetotalpercept[andbesimultaneouslyfelt]；oritmaybesoadaptedtooneeventastocause[p。637]ittobeperceivedimmediately，andthenthesecondeventcanbeperceivedonlyafteracertaintimeoflatency，duringwhichtheattentionreachesitseffectivemaximumforitanddiminishesforthefirstevent。Inthiscasetheeventsareperceivedastwo，andinsuccessiveorder——thatis，asseparatedbyatime-intervalinwhichattentionisnotsufficientlyaccommodatedtoeithertobringadistinctperceptionabout……Whilewearehurryingfromonetotheother，everythingbetweenthemvanishesinthetwilightofgeneralconsciousness。"[49]
Onemightcallthisthelawofdiscontinuoussuccessionintime，ofperceptstowhichwecannoteasilyattendatonce。Eachperceptthenrequiresaseparatebrain-process；andwhenonebrain-processisatitsmaximum，theotherwouldappearperforcetobeineitherawaningorawaxingphase。Ifourtheoryofthetime-feelingbetrue，emptytimemustthensubjectivelyappeartoseparatethetwopercepts，nomatterhowclosetogethertheymayobjectivelybe；for，accordingtothattheory，thefeelingofatime-durationistheimmediateeffectofsuchanoverlappingofbrain-pro-
[p。638]cessesofdifferentphase——whereverandfromwhatevercauseitmayoccur。
Topass，now，toconceptualprocesses:SupposeIthinkoftheCreation，thenoftheChristianera，thenofthebattleofWaterloo，allwithinafewseconds。Thesemattershavetheirdatesfaroutsidethespeciouspresent。
TheprocessesbywhichIthinkthem，however，alloverlap。Whatevents，then，doesthespeciouspresentseemtocontain？Simplymysuccessiveactsofthinkingtheselong-pastthings，notthelong-pastthingsthemselves。Astheinstantly-presentthoughtmaybeofalong-pastthing，sothejust-pastthoughtmaybeofanotherlong-pastthing。Whenalong-pasteventisreproducedinmemoryandconceivedwithitsdate，thereproductionandconceivingtraversethespeciouspresent。Theimmediatecontentofthelatteristhusallmydirectexperiences，whethersubjectiveorobjective。Someofthesemeanwhilemayberepresentativeofotherexperiencesindefinitelyremote。
Thenumberofthesedirectexperienceswhichthespeciouspresentandimmediately-intuitedpastmayembracemeasurestheextentofour’primary，’
asExnercallsit，or，asRichetcallsit，ofour’elementary’memory。[50]
Thesensationresultantfromtheoverlappingisthatofthedurationwhichtheexperiencesseemtofill。Asisthenumberofanylargersetofeventstothatoftheseexperiences，sowesupposeisthelengthofthatdurationtothisduration。Butofthelongerdurationwehavenodirect’realizingsense。’Thevariationsinourappreciationofthesameamountofrealtimemaypossiblybeexplainedbyalterationsintherateoffadingintheimages，producingchangesinthecomplicationofsuperposedprocesses，towhichchangeschangedstatesofconsciousnessmaycorrespond。Buthoweverlongwemayconceiveaspaceoftimetobe，theobjectiveamountofitwhichisdirectlyperceivedatanyonemomentbyuscanneverexceedthescopeofour’primarymemory’atthemomentinquestion。[51]
[p。639]Wehaveeveryreasontothinkthatcreaturesmaypossiblydifferenormouslyintheamountsofdurationwhichtheyintuitivelyfeel，andinthefinenessoftheeventsthatmayfillit。VonBæ；rhasindulged[52]
insomeinterestingcomputationsoftheeffectofsuchdifferencesinchangingtheaspectofNature。Supposewewereable，withinthelengthofasecond，tonote10，000eventsdistinctly，insteadofbarely10，asnow；ifourlifewerethendestinedtoholdthesamenumberofimpressions，itmightbe1000timesasshort。Weshouldlivelessthanamonth，andpersonallyknownothingofthechangeofseasons。Ifborninwinter，weshouldbelieveinsummeraswenowbelieveintheheatsoftheCarboniferousera。Themotionsoforganicbeingswouldbesoslowtooursensesastobeinferred，notseen。Thesunwouldstandstillinthesky，themoonbealmostfreefromchange，andsoon。Butnowreversethehypothesisandsupposeabeingtogetonlyone1000thpartofthesensationsthatwegetinagiventime，andconsequentlytolive1000timesaslong。Wintersandsummerswillbetohimlikequartersofanhour。Mushroomsandtheswifter-growingplantswillshootintobeingsorapidlyastoappearinstantaneouscreations；
annualshrubswillriseandfallfromtheearthlikerestlesslyboiling-watersprings；themotionsofanimalswillbeasinvisibleasaretousthemovementsofbulletsandcannon-balls；thesunwillscourthroughtheskylikeameteor，leavingafierytrailbehindhim，etc。Thatsuchimaginarycasesbarringthesuperhumanlongevitymayberealizedsomewhereintheanimalkingdom，itwouldberashtodeny。
"Agnat’swings，"saysMrSpencer，[53]"maketenorfifteenthousandstrokesasecond。Eachstrokeimpliesaseparatenervousaction。Eachsuchnervousactionorchangeinanervouscentreisprobablyasappreciablebythegnatasisaquickmovementofhisarmbyaman。Andifthis，oranythinglikethis，isthefact，thenthetimeoccupiedbyagivenexternalchange，measuredbymanymovementsintheonecase，mustseemmuchlongerthanintheothercase，whenmeasuredbyonemovement。"
Inhashish-intoxicationthereisacuriousincreaseintheapparenttime-perspective。Weutterasentence，andere[p。640]theendisreachedthebeginningseemsalreadytodatefromindefinitelylongago。Weenterashortstreet，anditisasifweshouldnevergettotheendofit。ThisalterationmightconceivablyresultfromanapproachtotheconditionofVonBæ；r’sandSpencer’sshort-livedbeings。Ifourdiscriminationofsuccessionsbecamefiner-grained，sothatwenotedtenstagesinaprocesswherepreviouslyweonlynotedone；andifatthesametimetheprocessesfadedtentimesasfastasbefore；wemighthaveaspeciouspresentofthesamesubjectivelengthasnow，givingusthesametime-feelingandcontainingasmanydistinguishablesuccessiveevents，butoutfromtheearlierendofitwouldhavedroopedninetenthsoftherealeventsitnowcontains。Theywouldhavefallenintothegeneralreservoirofmerelydatedmemories，reproducibleatwill。Thebeginningofoursentenceswouldhavetobeexpresslyrecalled；eachwordwouldappeartopassthroughconsciousnessatatenthofitsusualspeed。Theconditionwould，inshort，beexactlyanalogoustotheenlargementofspacebyamicroscope；fewerrealthingsatonceintheimmediatefieldofview，buteachofthemtakingupmorethanitsnormalroom，andmakingtheexcludedonesseemunnaturallyfaraway。
Underotherconditions，processesseemtofaderapidlywithoutthecompensatingincreaseinthesubdivisibilityofsuccessions。Heretheapparentlengthofthespeciouspresentcontracts。Consciousnessdwindlestoapoint，andlosesallintuitivesenseofthewhenceandwhitherofitspath。Expressactsofmemoryreplacerapidbird’s-eyeviews。Inmyowncase，somethinglikethisoccursinextremefatigue。Longillnessesproduceit。Occasionally，itappearstoaccompanyaphasia。[54]Itwouldbevaintoseek[p。641]
toimaginetheexactbrain-changeinanyofthesecases。Butwemustadmitthepossibilitythattosomeextentthevariationsoftime-estimatebetweenyouthandage，andexcitementandennui，areduetosuchcauses，moreimmediatethantotheoneweassignedsometimeago。
Butwhetherourfeelingofthetimewhichimmediately-past[55]eventshavefilledbeofsomethinglongorofsomethingshort，itisnotwhatitisbecausethoseeventsarepast，butbecausetheyhaveleftbehindthemprocesseswhicharepresent。Tothoseprocesses，howevercaused，themindwouldstillrespondbyfeelingaspeciouspresent，withonepartofitjustvanishingorvanishedintothepast。AstheCreatorissupposedtohavemadeAdamwithanavel——signofabirthwhichneveroccurred——soHemightinstantaneouslymakeamanwithabraininwhichwereprocessesjustlikethe’fading’onesofanordinarybrain。
Thefirstrealstimulusaftercreationwouldsetupaprocessadditionaltothese。Theprocesseswouldoverlap；andthenew-createdmanwouldunquestionablyhavethefeeling，attheveryprimalinstantofhislife，ofhavingbeeninexistencealreadysomelittlespaceoftime。
[p。642]Letmesumup，now，bysayingthatweareconstantlyconsciousofacertainduration——thespeciouspresent——varyinginlengthfromafewsecondstoprobablynotmorethanaminute，andthatthisdurationwithitscontentperceivedashavingonepartearlierandtheotherpartlateristheoriginalintuitionoftime。Longertimesareconceivedbyadding，shorteronesbydividing，portionsofthisvaguelyboundedunit，andarehabituallythoughtbyussymbolically。Kant’snotionofanintuitionofobjectivetimeasaninfinitenecessarycontinuumhasnothingtosupportit。Thecauseoftheintuitionwhichwereallyhavecannotbethedurationofourbrain-processesorourmentalchanges。Thatdurationisrathertheobjectoftheintuitionwhich，beingrealizedateverymomentofsuchduration，mustbeduetoapermanentlypresentcause。Thiscause——probablythesimultaneouspresenceofbrain-processesofdifferentphase-fluctuates；andhenceacertainrangeofvariationintheamountoftheintuition，andinitssubdivisibility，accrues。
Footnotes[1]ThischapterisreprintedalmostverbatimfromtheJournalofSpeculativePhilosophy，vol。XX。p。374。
[2]JamesMill，Analysis，vol。I。p。319J。S。Mill’sEdition。
[3]"WhatIfind，whenIlookatconsciousnessatall，is，thatwhatIcannotdivestmyselfof，ornothaveinconsciousness，ifIhaveconsciousnessatall，isasequenceofdifferentfeelings……Thesimultaneousperceptionofbothsub-feelings，whetheraspartsofacoexistenceorofasequence，isthetotalfeeling——theminimumofconsciousness——andthisminimumhasduration……Time-duration，however，isinseparablefromtheminimum，notwithstandingthat，inanisolatedmoment，wecouldnottellwhichpartofitcamefirst，whichlast……Wedonotrequiretoknowthatthesub-feelingscomeinsequence，firstone，thentheother；nortoknowwhatcominginsequencemeans。Butwehave，inanyartificiallyisolatedminimumofconsciousness，therudimentsoftheperceptionofformerandlatterintime，inthesub-feelingthatgrowsfainter，andthesub-feelingthatgrowsstronger，andthechangebetweenthem……
"Inthenextplace，Iremarkthattherudimentsofmemoryareinvolvedintheminimumofconsciousness。Thefirstbeginningsofitappearinthatminimum，justasthefirstbeginningsofperceptiondo。Aseachmemberofthechangeordifferencewhichgoestocomposethatminimumistherudimentofasingleperception，sothepriorityofonemembertotheother，althoughbotharegiventoconsciousnessinoneempiricalpresentmoment，istherudimentofmemory。Thefactthattheminimumofconsciousnessisdifferenceorchangeinfeelings，istheultimateexplanationofmemoryaswellasofsingleperceptions。Aformerandalatterareincludedintheminimumofconsciousness；andthisiswhatismeantbysayingthatallconsciousnessisintheformoftime，orthattimeistheformoffeeling，theformofsensibility。Crudelyandpopularlywedividethecourseoftimeintopast，present，andfuture；but，strictlyspeaking，thereisnopresent；
itiscomposedofpastandfuturedividedbyanindivisiblepointorinstant。
Thatinstant，ortime-point，isthestrictpresent。Whatwecall，loosely，thepresent，isanempiricalportionofthecourseoftime，containingatleastaminimumofconsciousness，inwhichtheinstantofchangeisthepresenttime-point……Ifwetakethisasthepresenttime-point，itisclearthattheminimumoffeelingcontainstwoportions——asub-feelingthatgoesandasub-feelingthatcomes。Oneisremembered，theotherimagined。
Thelimitsofbothareindefiniteatbeginningandendoftheminimum，andreadytomeltintootherminima，proceedingfromotherstimuli。
"Timeandconsciousnessdonotcometousreadymarkedoutintominima；
wehavetodothatbyreflection，askingourselves，Whatistheleastempiricalmomentofconsciousness？Thatleastempiricalmomentiswhatweusuallycallthepresentmoment；andeventhisistoominuteforordinaryuse；
thepresentmomentisoftenextendedpracticallytoafewseconds，orevenminutes，beyondwhichwespecifywhatlengthoftimewemean，asthepresenthour，orday，oryear，orcentury。
"Butthispopularwayofthinkingimposesitselfongreatnumbersevenofphilosophically-mindedpeople，andtheytalkaboutthepresentasifitwasadatum——asiftimecametousmarkedintopresentperiodslikeameasuring-tape。"S。H。Hodgson:PhilosophyofReflection，vol。I。pp。248-254。
"Therepresentationoftimeagreeswiththatofspaceinthatacertainamountofitmustbepresentedtogether——includedbetweenitsinitialandterminallimit。Acontinuousideation，flowingfromonepointtoanother，wouldindeedoccupytime，butnotrepresentit，foritwouldexchangeoneelementofsuccessionforanotherinsteadofgraspingthewholesuccessionatonce。Bothpoints——thebeginningandtheend——areequallyessentialtotheconceptionoftime，andmustbepresentwithequalclearnesstogether。"Herbart:Psychol。alsW。，&；sect；115。
"Assumethat……similarpendulum-strokesfolloweachotheratregularintervalsinaconsciousnessotherwisevoid。Whenthefirstoneisover，animageofitremainsinthefancyuntilthesecondsucceeds。This，then，reproducesthefirstbyvirtueofthelawofassociationbysimilarity，butatthesametimemeetswiththeaforesaidpersistingimage……Thusdoesthesimplerepetitionofthesoundprovidealltheelementsoftime-perception。
Thefirstsound[asitisrecalledbyassociation]givesthebeginning，thesecondtheend，andthepersistentimageinthefancyrepresentsthelengthoftheinterval。Atthemomentofthesecondimpression，theentiretime-perceptionexistsatonce，forthenallitselementsarepresentedtogether，thesecondsoundandtheimageinthefancyimmediately，andthefirstimpressionbyreproduction。But，inthesameact，weareawareofastateinwhichonlythefirstsoundexisted，andofanotherinwhichonlyitsimageexistedinthefancy。Suchaconsciousnessasthisisthatoftime……Initnosuccessionofideastakesplace。"Wundt:
Physiol。Psych。，1sted。pp。681-2。Noteheretheassumptionthatthepersistenceandthereproductionofanimpressionaretwoprocesseswhichmaygoonsimultaneously。AlsothatWundt’sdescriptionismerelyanattempttoanalyzethe’deliverance’ofatime-perception，andnoexplanationofthemannerinwhichitcomesabout。
[4]TheAlternative，p。167。
[5]Locke，inhisdimway，derivedthesenseofdurationfromreflectiononthesuccessionofourideasEssay，bookII。chap。XIV。
&；sect；3；chap。XV。&；sect；12。Reidjustlyremarksthatiftensuccessiveelementsaretomakeduration，"thenonemustmakeduration，otherwisedurationmustbemadeupofpartsthathavenoduration，whichisimpossible……Iconclude，therefore，thattheremustbedurationineverysingleintervalorelementofwhichthewholedurationismadeup。Nothing，indeed，ismorecertainthanthateveryelementarypartofdurationmusthaveduration，aseveryelementarypartofextensionmusthaveextension。Now，itmustbeobservedthatintheseelementsofduration，orsingleintervalsofsuccessiveideas，thereisnosuccessionofideas，yetwemustconceivethemtohaveduration；whencewemayconcludewithcertaintythatthereisaconceptionofdurationwherethereisnosuccessionofideasinthemind。"IntellectualPowers。essayIII。chap。V。’’Qu’onnecherchepoint，"saysRoyerCollardintheFragmentsaddedtoJouffroy’sTranslationofReid，"laduré；edanslasuccession；
onnel’ytrouverajamais；laduré；eapré；cé；dé；
lasuccession；innotiondeladuré；eapré；cé；dé；
lanotiondelasuccession。Elleenestdonctout-à；faitindé；pendante，dira-t-on？Oui，elleenesttout-à；-faitindé；pendante。"
[6]Physiol。Psych。，"II。54，55。
[7]Ibid。II。213。
[8]PhilosophischeStudien，II。362。
[9]Countingwasofcoursenotpermitted。Itwouldhavegivenasymbolicconceptandnointuitiveorimmediateperceptionofthetotalityoftheseries。Withcountingwemayofcoursecomparetogetherseriesofanylength——serieswhosebeginningshavefadedfromourmind，andofwhosetotalityweretainnosensibleimpressionatall。Tocountaseriesofclicksisanaltogetherdifferentthingfrommerelyperceivingthemasdiscontinuous。Inthelattercaseweneedonlybeconsciousofthebitsofemptydurationbetweenthem；intheformerwemustperformrapidactsofassociationbetweenthemandasmanynamesofnumbers。
[10]EstelinWundt’sPhilosophischeStudien，II。
50。Mehner，ibid。II。571。InDietze’sexperimentsevennumbersofstrokeswerebettercaughtthanoddones，bytheear。Therapidityoftheirsequencehadagreatinfluenceontheresult。Atmorethan4secondsapartitwasimpossibletoperceiveseriesofthemasunitsinallcf。Wundt，Physiol。Psych。，II。214。Theyweresimplycountedassomanyindividualstrokes。Below0。21to0。11second，accordingtotheobserver，judgmentagainbecameconfused。Itwasfoundthattherateofsuccessionmostfavorableforgraspinglongserieswaswhenthestrokesweresoundedatintervalsoffrom0。3"to0。18"apart。Seriesof4，6，8，16weremoreeasilyidentifiedthanseriesof10，12，14，18。Thelattercouldhardlybeclearlygraspedatall。Amongoddnumbers，3，5，7weretheserieseasiestcaught；next，9，15；hardestofall，11and13；and17wasimpossibletoapprehend。
[11]Theexactintervalofthesparkswas0。00205"。
Thedoublenessoftheirsnapwasusuallyreplacedbyasingle-seemingsoundwhenitfellto0。00198"，thesoundbecominglouderwhenthesparksseemedsimultaneous。Thedifferencebetweenthesetwointervalsisonly7/100000ofasecond；and，asExnerremarks，ourearandbrainmustbewonderfullyefficientorganstogetdistinctfeelingsfromsoslightanobjectivedifferenceasthis。SeePflü；ger’sArchiv，Bd。XI。
[12]Ibid。p。407。Whenthesparksfellsoclosetogetherthattheirirradiation-circlesoverlapped，theyappearedlikeonesparkmovingfromthepositionofthefirsttothatofthesecond；andtheymightthenfolloweachotherascloseas0。015"withoutthedirectionofthemovementceasingtobeclear。Whenonesparkfellonthecentre，theotheronthemargin，oftheretina，thetime-intervalforsuccessiveapprehensionhadtoberaisedto0。076"。
[13]HallandJastrow:StudiesofRhythm。Mind，XI。
58。
[14]Nevertheless，multitudinousimpressionsmaybefeltasdiscontinuous，thoughseparatedbyexcessivelyminuteintervalsoftime。Grü；nhagensaysPflü；ger’sArchiv，VI。175that10，000
electricshocksasecondarefeltasinterrupted，bythetongue！。VonWittichibid。II。329，thatbetween1000and2000strokesasecondarefeltasdiscretebythefinger。W。Preyer，ontheotherhandDieGrenzendesEmpfindungsvermö；gens，etc。，1868，p。15，makescontactsappearcontinuoustothefingerwhen36。8ofthemfollowinasecond。Similarly，MachWienerSitzgsb。，LI。2，142givesabout36。LalanneComptesRendus，LXXXII。p。1314foundsummationoffinger-contactsafter22repetitionsinasecond。Suchdiscrepantfiguresareofdoubtfulworth。Ontheretina20to30impressionsasecondattheveryutmostcanbefeltasdiscretewhentheyfallonthesamespot。Theear，whichbeginstofusestimulitogetherintoamusicaltonewhentheyfollowattherateofalittleover30asecond，canstillfeel132ofthemasecondasdiscontinuouswhentheytaketheshapeof’beats’Helmholtz，Tonempfindungen，3ded。p。270。
[15]Pflü；ger’sArchiv，XI。428。AlsoinHerrmann’sHdbh。d。Physiol。，2Bd。，I。Thl。pp。260-262。
[16]Pflü；ger’sArchiv，VII。639。TigerstedtBihangtillKongl。SvenskaVetenskaps-Akad。Handl。，Bd。8，Hä；fte2，Stockholm，1884revisesExner’sfigures，andshowsthathisconclusionsareexaggerated。
AccordingtoTigerstedt，twoobserversalmostalwaysrightlyappreciated0。05"or0。06"ofreaction-timedifference。Halfthetimetheydiditrightlywhenthedifferencesankto0。03"，thoughfrom0。03"and0。06"differenceswereoftennotnoticedatall。BuccolafoundLeLeggedelTemponeiFenomenidelPensiero，Milano，1883，p。371that，aftermuchpracticeinmakingrapidreactionsuponasignal，heestimateddirectly，infigures，hisownreaction-time，in10experiments，withanerroroffrom0。010"to0。018"；
in6，withoneof0。005"to0。009"；inone，withoneof0。002"；andin3，withoneof0。003"。
[17]"Mind，XI。611886。
[18]Mach，WienerSitzungsb。，LI。2。1331865；Estel，loc。cit。p。65；Mehner，loc。cit。p。586；Buccola，op。cit。p378。Fechnerlaborstoprovethathislawisonlyoverlaidbyotherinterferinglawsinthefiguresrecordedbytheseexperimenters；
buthiscaseseemstometobeoneofdesperateinfatuationwithahobby。
SeeWundt’sPhilosophischeStudien，III。1。
[19]CuriousdiscrepanciesexistbetweentheGermanandtheAmericanobserverswithrespecttothedirectionoftheerrorbelowandabovethepointofindifference——differencesperhapsduetothefatigueinvolvedintheAmericanmethod。TheGermanslengthenedintervalsbelowitandshortenedthoseabove。WithsevenAmericansexperimentedonbyStevensthiswasexactlyreversed。TheGermanmethodwastopassivelylistentotheintervals，thenjudge；theAmericanwastoreproducethemactivelybymovementsofthehand。InMehner’sexperimentstherewasfoundasecondindifference-pointatabout5seconds，beyondwhichtimeswerejudgedagaintoolong。Glass，whoseworkonthesubjectisthelatestPhilos。Studien，IV。423，foundwhencorrectionswereallowedforthatalltimesexcept0。8sec。wereestimatedtooshort。Hefoundaseriesofpointsofgreatestrelativeaccuracyviz。，at1。5，2。5，3。75，5，6。25，etc。，secondsrespectively[]，and[sic]thoughtthathisobservationsroughlycorroboratedWeber’slaw。As’maximum’and’minimum’areprintedinterchangeablyinGlass’sarticleitishardtofollow。
[20]WithVierordtandhispupilstheindifferencepointlayashighasfrom1。5sec。to4。9sec。，accordingtotheobservercf。DerZeitsinn，1868，p。112。Inmostoftheseexperimentsthetimeheardwasactivelyreproduced，afterashortpause，bymovementsofthehand，whichwererecorded。WundtgivesgoodreasonsPhysiol。Psych。，II。
289，290forrejectingVierordt’sfiguresaserroneous。Vierordt’sbook，itshouldbesaid，isfullofimportantmatter，nevertheless。
[21]Physiol。Psych。，II。286，290。
[22]PhilosophischeStudien，I。86。
[23]Mind，XI。400。
[24]Loc。cit。p。144。
[25]Op。cit。p。376。Mach’sandBuccola’sfigures，itwillbeobserved，areaboutonehalfoftherest——
sub-multiples，therefore。Itoughttobeobserved，however，thatBuccola’sfigurehaslittlevalue，hisobservationsnotbeingwellfittedtoshowthisparticularpoint。
[26]Estel’sfiguresledhimtothinkthatallthemultiplesenjoyedthisprivilege；withMehner，ontheotherhand，onlytheoddmultiplesshoweddiminutionoftheaverageerror；thus，0。71，2。15，3。55，5，6。4，7。8，9。3，and10。65secondwererespectivelyregisteredwiththeleasterror。Cf。Phil。Studien，II。pp。57，562-565。
[27]Cf。especiallypp。558-561。
[28]Wundt:Physiol。Psych。，II。287。HallandJastrow:
Mind，XI。62。
[29]Mehner:loc。cit。p。553。
[30]"Thenumberofdistinguishabledifferencesofspeedbetweentheselimitsis，ashetakescaretoremark，verymuchlargerthan7DerZeitsinn，p。137。
[31]P。19，&；sect；18，112。
[32]IleavethetextjustasitwasprintedintheJournalofSpeculativePhilosophyfor’Oct。1886’in1887。SincethenMü；nsterberginhismasterlyBeiträ；gezurexperimentellenPsychologieHeft2，1889seemstohavemadeitclearwhatthesensiblechangesarebywhichwemeasurethelapseoftime。Whenthetimewhichseparatestwosensibleimpressionsislessthanonethirdofasecond，hethinksitisalmostentirelytheamounttowhichthememory-imageofthefirstimpressionhadfadedwhenthesecondoneovertakesit，whichmakesusfeelhowwidetheyareapartp。29。Whenthetimeislongerthanthis，werely，hethinks，exclusivelyuponthefeelingsofmusculartensionandrelaxation，whichweareconstantlyreceivingalthoughwegivetothemsolittleofourdirectattention。Thesefeelingsareprimarilyinthemusclesbywhichweadoptoursense-organsinattendingtothesignalsused，someofthemusclesbeingintheeyeandearthemselves，someoftheminthehead，neck，etc。Weherejudgetwotime-intervalstobeequalwhenbetweenthebeginningandendofeachwefeelexactlysimilarrelaxationsandsubsequentexpectanttensionsofthesemusclestohaveoccurred。Inreproducingintervalsourselveswetrytomakeourfeelingsofthissortjustwhattheywerewhenwepassivelyheardtheinterval。
Thesefeelingsbythemselves，however，canonlybeusedwhentheintervalsareveryshort，forthetensionanticipatoryoftheterminalstimulusnaturallyreachesitsmaximumverysoon。Withlongerintervalswetakethefeelingofourinspirationsandexpirationsintoaccount。Withourexpirationsalltheothermusculartensionsinourbodyundergoarhythmicaldecrease；
withourinspirationsthereversetakesplace。When，therefore，wenoteatime-intervalofseveralsecondswithintenttoreproduceit，whatweseekistomaketheearlierandlaterintervalagreeinthenumberandamountoftheserespiratorychangescombinedwithsense-organadjustmentswithwhichtheyarefilled。Mü；nsterberghasstudiedcarefullyinhisowncasethevariationsoftherespiratoryfactor。Theyaremany；buthesumsuphisexperiencebysayingthatwhetherhemeasuredbyinspirationsthatweredividedbymomentarypausesintosixparts，orbyinspirationsthatwerecontinuous；whetherwithsensorytensionduringinspirationandrelaxationduringexpiration，orbytensionduringbothinspirationandexpiration，separatedbyasuddeninterpolatedrelaxation；whetherwithspecialnoticetakenofthecephalictensions，orofthoseinthetrunkandshoulders，inallcasesalikeandwithoutexceptionheinvoluntarilyendeavored，wheneverhecomparedtwotimesortriedtomakeonethesameastheother，togetexactlythesamerespiratoryconditionsandconditionsoftension，allthesubjectiveconditions，inshort，exactlythesameduringthesecondintervalastheywereduringthefirst。Mü；nsterbergcorroboratedhissubjectiveobservationsbyexperiments。Theobserverofthetimehadtoreproduceasexactlyaspossibleanintervalbetweentwosharpsoundsgivenhimbyanassistant。Theonlyconditionimposeduponhimwasthatheshouldnotmodifyhisbreathingforthepurposesofmeasurement。
Itwasthenfoundthatwhentheassistantbrokeinatrandomwithhissignals，thejudgmentoftheobserverwasvastlylessaccuratethanwhentheassistantcarefullywatchedtheobserver’sbreathingandmadeboththebeginningofthetimegivenhimandthatofthetimewhichhewastogivecoincidewithidenticalphasesthereof——Finally，Mü；nsterbergwithgreatplausibilitytriestoexplainthediscrepanciesbetweentheresultsofVierordt，Estel，Mehner，Glass，etc。，asduetothefactthattheydidnotallusethesamemeasure。Somebreathealittlefaster，somealittleslower。Somebreaktheirinspirationsintotwoparts，somedonot，etc。Thecoincidenceoftheobjectivetimesmeasuredwithdefinitenaturalphasesofbreathingwouldveryeasilygiveperiodicalmaximaoffacilityinmeasuringaccurately。
[33]"Anyonewishingyetfurtherexamplesofthismentalsubstitutionwillfindoneonobservinghowhabituallyhethinksofthespacesontheclock-faceinsteadoftheperiodstheystandfor；
how，ondiscoveringittobehalfanhourlaterthanhesupposed，hedoesnotrepresentthehalfhourinitsduration，butscarcelypassesbeyondthesignofitmarkedbythefinger。"H。Spencer:Psychology，&；sect；
336。
[34]TheonlyobjectionstothiswhichIcanthinkofare:1Theaccuracywithwhichsomemenjudgeofthehourofdayornightwithoutlookingattheclock；2thefacultysomehaveofwakingatapreappointedhour；3theaccuracyoftime-perceptionreportedtoexistincertaintrance-subjects。Itmightseemthatinthesepersonssomesortofasub-consciousrecordwaskeptofthelapseoftimeperse。
Butthiscannotbeadmitteduntilitisprovedthattherearenophysiologicalprocesses，thefeelingofwhosecoursemayserveasasignofhowmuchtimehassped，andsoleadustoinferthehour。Thattherearesuchprocessesitishardlypossibletodoubt。Aningeniousfriendofminewaslongpuzzledtoknowwhyeachdayoftheweekhadsuchacharacteristicphysiognomytohim。ThatofSundaywassoonnoticedtobeduetothecessationofthecity’srumbling，andthesoundofpeople’sfeetshufflingonthesidewalk；ofMonday，tocomefromtheclothesdryingintheyardandcastingawhitereflectionontheceiling；ofTuesday，toacausewhichIforget；
andIthinkmyfrienddidnotgetbeyondWednesday。Probablyeachhourinthedayhasformostofussomeouterorinnersignassociatedwithitascloselyasthesesignswiththedaysoftheweek。Itmustbeadmitted，afterall，however，thatthegreatimprovementofthetime-perceptionduringsleepandtranceisamysterynotasyetclearedup。AllmylifeIhavebeenstruckbytheaccuracywithwhichIwillwakeatthesameexactminutenightafternightandmorningaftermorning，ifonlythehabitfortuitouslybegins。Theorganicregistrationinmeisindependentofsleep。
AfterlyinginbedalongtimeawakeIsuddenlyrisewithoutknowingthetime，andfordaysandweekstogetherwilldosoatanidenticalminutebytheclock，asifsomeinwardphysiologicalprocesscausedtheactbypunctuallyrunningdown——Idiotsaresaidsometimestopossessthetime-measuringfacultyinamarkeddegree。Ihaveaninterestingmanuscriptaccountofanidiotgirlwhichsays:"Shewaspunctualalmosttoaminuteinherdemandforfoodandotherregularattentions。Herdinnerwasgenerallyfurnishedherat12。30P。M。，andatthathourshewouldbegintoscreamifitwerenotforthcoming。IfonFast-dayorThanksgivingitweredelayed，inaccordancewiththeNewEnglandcustom，shescreamedfromherusualdinner-houruntilthefoodwascarriedtoher。Onthenextday，however，sheagainmadeknownherwantspromptlyat12。30。Anyslightattentionshownherononedaywasdemandedonthenextatthecorrespondinghour。Ifanorangeweregivenherat4P。M。onWednesday，atthesamehouronThursdayshemadeknownherexpectation，andifthefruitwerenotgivenhershecontinuedtocallforitatintervalsfortwoorthreehours。AtfouronFridaytheprocesswouldberepeatedbutwouldlastlesslong；andsoonfortwoorthreedays。Ifoneofhersistersvisitedheraccidentallyatacertainhour，thesharppiercingscreamwassuretosummonheratthesamehourthenextday，"etc。，etc——FortheseobscuremattersconsultC。DuPrel:ThePhilosophyofMysticism，chap。III。&；sect；1。
[35]IdealeFragen1878。p。219Essay，’ZeitundWeile’。
[36]RevuePhilosophique，vol。III。p。496。
[37]"Emptytimeismoststronglyperceivedwhenitcomesasapauseinmusicorinspeech。Supposeapreacherinthepulpit，aprofessorathisdesk，tostickstillinthemidstofhisdiscourse；
orletacomposerasissometimespurposelydonemakeallhisinstrumentsstopatonce；weawaiteveryinstanttheresumptionoftheperformance，and，inthisawaiting，perceive，morethaninanyotherpossibleway，theemptytime。Tochangetheexample，let，inapieceofpolyphonicmusic——afigure，forinstance，inwhichatangleofmelodiesareunderway——suddenlyasinglevoicebeheard，whichsustainsalongnote，whileallelseishushed……Thisonenotewillappearveryprotracted——
why？Becauseweexpecttohearaccompanyingitthenotesoftheotherinstruments，buttheyfailtocome。"Herbart:Psychol。alsW。，§；115。——
ComparealsoMü；nsterberg，Beiträ；ge，Heft2，p。41。
[38]Anightofpainwillseemterriblylong；wekeeplookingforwardtoamomentwhichnevercomes——themomentwhenitshallcease。ButtheodiousnessofthisexperienceisnotnamedennuiorLangweile，liketheodiousnessoftimethatseemslongfromitsemptiness。Themorepositiveodiousnessofthepain，rather，iswhattingesourmemoryofthenight。Whatwefeel，asProf。Lazarussaysopcit。
p。202，isthelongtimeofthesuffering，notthesufferingofthelongtimeperse。
[39]Onthesevariationsoftime-estimate，cf。Romanes，ConsciousnessofTime。inMind，vol。III。p。297；J。Sully，Illusions，pp。245-261，302-305；W。Wundt，Physiol。Psych。，II。287，288；besidestheessaysquotedfromLazarusandJanet。InGerman，thesuccessorsofHerbarthavetreatedofthissubject:compareVolkmann’sLehrbuchd。Psych。，&；sect；89，andforreferencestootherauthorshisnote3tothissection。
LindnerLbh。d。empir。Psych。，asaparalleleffect，instancesAlexandertheGreat’slifethirty-threeyears，whichseemstousasifitmustbelong，becauseitwassoeventful。SimilarlytheEnglishCommonwealth，etc。
[40]PhysiolOptik，p。445。
[41]Succession，timeperse，isnoforce。Ourtalkaboutitsdevouringtooth，etc。，isallelliptical。Itscontentsarewhatdevour。Thelawofinnertiaisincompatiblewithtime’sbeingassumedasanefficientcauseofanything。
[42]Lehrbuchd。Psych。，&；sect；87。ComparealsoH。Lotze，Metaphysik，&；sect；154。
[43]Thecauseoftheperceiving，nottheobjectperceived！
[44]"’Nomore’and’notyet’arethepropertime-feelings，andweareawareoftimeinnootherwaythanthroughthesefeelings，"
saysVolkmannPsychol。，&；sect；87。This，whichisnotstrictlytrueofourfeelingoftimeperse，asanelementarybitofduration，istrueofourfeelingofdateinitsevents。
[45]Weconstructthemilesjustasweconstructtheyears。Travellinginthecarsmakesasuccessionofdifferentfieldsofviewpassbeforeoureyes。Whenthosethathavepassedfrompresentsightreviveinmemory，theymaintaintheirmutualorderbecausetheircontentsoverlap。Wethinkthemashavingbeenbeforeorbehindeachother；and，fromthemultitudeoftheviewswecanrecallbehindtheonenowpresented，wecomputethetotalspacewehavepassedthrough。
Itisoftensaidthattheperceptionoftimedevelopslaterthanthatofspace，becausechildrenhavesovagueanideaofalldatesbeforeyesterdayandafterto-morrow。Butnovaguerthantheyhaveofextensionsthatexceedasgreatlytheirunitofspace-intuition。RecentlyIheardmychildoffourtellavisitorthathehadbeen’asmuchasoneweek’inthecountry。
Ashehadbeentherethreemonths，thevisitorexpressedsurprise；whereuponthechildcorrectedhimselfbysayinghehadbeenthere’twelveyears。’
ButthechildmadeexactlythesamekindofmistakewhenheaskedifBostonwasnotonehundredmilesfromCambridge，thedistancebeingthreemiles。
[46]Mostoftheseexplanationssimplygivethesignswhich，adheringtoimpressions，leadustodatethemwithinaduration，or，inotherwords，toassigntothemtheirorder。Whyitshouldbeatime-order，however，isnotexplained。Herbart’swould-beexplanationisasimpledescriptionoftime-perception。Hesaysitcomeswhen，withthelastmemberofaseriespresenttoourconsciousness，wealsothinkofthefirst；andthenthewholeseriesrevivesinourthoughtatonce，butwithstrengthdiminishinginthebackwarddirectionPsychol。alsWiss。，&；sect；115；Lehrb。
zurPsychol。，&；sect；&；sect；171，172，175。SimilarlyDrobisch，whoaddsthattheseriesmustappearasonealreadyelapseddurchlaufene，awordwhichshowsevenmoreclearlythequestion-beggingnatureofthissortofaccountEmpirischePsychol。，&；sect；59。Th。Waitzisguiltyofsimilarquestion-beggingwhenheexplainsourtime-consciousnesstobeengenderedbyasetofunsuccessfulattemptstomakeourperceptsagreewithourexpectationsLehrb。d。Psychol。，&；sect；52。Volkmann’smythologicalaccountofpastrepresentationsstrivingtodrivepresentonesoutoftheseatofconsciousness，beingdrivenbackbythem，etc。，suffersfromthesamefallacyPsychol。，&；sect；87。Butallsuchaccountsagreeinimplyingonefact——viz。，thatthebrain-processesofvariouseventsmustbeactivesimultaneously，andinvaryingstrength，foratime-perceptiontobepossible。Laterauthorshavemadethisideamoreprecise。Thus，Lipps:
"Sensationsarise，occupyconsciousness，fadeintoimages，andvanish。
Accordingastwoofthem，aandb，gothroughthisprocesssimultaneously，orasoneprecedesorfollowstheother，thephasesoftheirfadingwillagreeordiffer；andthedifferencewillbeproportionaltothetime-differencebetweentheirseveralmomentsofbeginning。Thustherearedifferencesofqualityintheimages，whichthemindmaytranslateintocorrespondingdifferencesoftheirtemporalorder。
Thereisnootherpossiblemiddletermbetweentheobjectivetime-relationsandthoseinthemindthanthesedifferencesofphase。"GrundtatsachendesSeelenlebens，p。588。Lippsaccordinglycallsthem’temporalsigns，’
andhastensexplicitlytoaddthatthesoul’stranslationoftheirorderofstrengthintoatime-orderisentirelyinexplicablep。591。M。Guyau’saccountRevuePhilosophique，XIX。353hardlydiffersfromthatofhispredecessors，exceptinpicturesquenessofstyle。Everychangeleavesaseriesoftrainé；eslumineusesinthemindlikethepassageofshootingstars。Eachimageisinamorefadingphase，accordingasitsoriginalwasmoreremote。Thisgroupofimagesgivesduration，themeretime-form，the’bed’oftime。Thedistinctionofpast，present，andfuturewithinthebedcomesfromouractivenature。ThefutureaswithWaitz
iswhatIwant，buthavenotyetgot，andmustwaitfor。Allthisisdoubtlesstrue，butisnoexplanation。
Mr。Wardgives，inhisEncyclopæ；diaBritannicaarticlePsychology。
p。65，col。1，astillmorerefinedattempttospecifythe’temporalsign。’