Howisthisconceptioneasierthantheother？Westillhavementally。to
　　representabodyasactingwhereitisnot，andintheabsenceofanything
　　bywhichitsactionmaybetransferred;andwhatmattersitwhetherthis
　　takesplaceonalargeorasmallscale？Thusweareobligedtoconclude
　　thatmatter，whetherponderableorimponderable，andwhetheraggregatedor
　　initshypotheticalunits，actsonmatterthroughabsolutelyvacantspace;andyetthisconclusionisunthinkable。Anotherdifficultyofconception，converseinnaturebutequallyinsurmountable，
　　mustbeadded。If，ontheonehand，wecannotinthoughtseematteracting
　　uponmatterthroughvacantspace;ontheotherhand，itisincomprehensible
　　thatthegravitationofoneparticleofmattertowardsanother，andtowards
　　allothers，shouldbethesamewhethertheinterveningspaceisfilledwith
　　matterornot。Iliftfromtheground，andcontinuetohold，apoundweight。
　　Now，intothevacancybetweenitandtheground，isintroducedamassof
　　matterofanykindwhatever，inanystatewhatever;andthegravitationof
　　theweightisentirelyunaffected。Eachindividualoftheinfinityofparticles
　　composingtheEarthactsonthepoundinabsolutelythesameway，whatever
　　intervenes，orifnothingintervenes。Througheightthousandmilesofthe
　　Earth'ssubstance，eachmoleculeattheantipodesaffectseachmoleculeof
　　theweight，inutterindifferencetothefullnessoremptinessofthespace
　　betweenthem。Sothateachportionofmatterinitsdealingswithremote
　　portions，treatsallinterveningportionsasthoughtheydidnotexist;and
　　yet，atthesametime，itrecognizestheirexistencewithscrupulousexactnessinitsdirectdealingswiththem。WhilethenitisimpossibletoformanyideaofForceinitself，itisequallyimpossibletocomprehenditsmodeofexercise。§19。Turningnowfromtheoutertotheinnerworld，letuscontemplate，
　　nottheagenciestowhichweascribeoursubjectivemodifications，butthe
　　subjectivemodificationsthemselves。Theseconstituteaseries。Difficult
　　aswefinditdistinctlytoindividualizethem，itisneverthelessbeyondquestionthatourstatesofconsciousnessoccurinsuccession。Isthischainofstatesofconsciousnessinfiniteorfinite？Wecannot
　　sayinfinite;notonlybecausewehaveindirectlyreachedtheconclusion
　　thattherewasaperiodwhenitcommenced，butalsobecauseallinfinity
　　isinconceivable——aninfiniteseriesincluded。Ifwesayfinitewesay
　　itinferentially;forwehavenodirectknowledgeofeitherofitsends。
　　Gobackinmemoryasfaraswemay，wearewhollyunabletoidentifyour
　　firststatesofconsciousness。Similarlyattheotherextreme。Weinfera
　　terminationtotheseriesatafuturetime，butcannotdirectlyknowit;
　　andwecannotreallylayholdofthattemporaryterminationreachedatthe
　　presentmoment。Forthestateofconsciousnessrecognizedbyusasourlast，
　　isnottrulyourlast。Thatanymentalaffectionmaybeknownasoneofthe
　　series，itmustberemembered——representedinthought，notpresented。The
　　trulylaststateofconsciousnessisthatwhichispassingintheveryact
　　ofcontemplatingastatejustpast——thatinwhichwearethinkingofthe
　　onebeforeasthelast。Sothattheproximateendofthechangeeludesus，aswellastheremoteend。"But，"itmaybesaid，"thoughwecannotdirectlyknow
　　consciousnesstobefiniteinduration，becauseneitherofitslimitscan
　　beactuallyreached，yetwecanverywellconceiveittobeso。"No:
　　noteventhisistrue。Wecannotconceivetheterminationsofthatconsciousness
　　whichalonewereallyknow——ourown——anymorethanwecanperceiveits
　　terminations。Forintruththetwoactsarehereone。Ineithercasesuch
　　terminationsmustbe，asabovesaid，notpresentedinthought，butrepresented;
　　andtheymustberepresentedasintheactofoccurring。Nowtorepresent
　　theterminationofconsciousnessasoccurringinourselves，istothinkof
　　ourselvesascontemplatingthecessationofthelaststateofconsciousness;
　　andthisimpliesasupposedcontinuanceofconsciousnessafteritslaststate，whichisabsurd。Hence，whileweareunabletobelieveortoconceivethattheduration
　　ofconsciousnessisinfinite，weareequallyunableeithertoknowitas
　　finite，ortoconceiveitasfinite:wecanonlyinferfromindirectevidencethatitisfinite。§20。Nordowemeetwithanygreatersuccesswhen，insteadofthe
　　extentofconsciousness，weconsideritssubstance。Thequestion——What
　　isthisthatthinks？admitsofnobettersolutionthanthequestiontowhichwehavejustfoundnonebutinconceivableanswers。Theexistenceofeachindividualasknowntohimself，hasalwaysbeen
　　heldthemostincontrovertibleoftruths。Tosay——"Iamassureof
　　itasIamsurethatIexist，"is，incommonspeech，themostemphatic
　　expressionofcertainty。Andthisfactofpersonalexistence，testifiedto
　　bytheuniversalconsciousnessofmen，hasbeenmadethebasisofmorephilosophiesthanone。Beliefintherealityofselfcannot，indeed，beescapedwhilenormal
　　consciousnesscontinues。Whatshallwesayofthesesuccessiveimpressions
　　andideaswhichconstituteconsciousness？Aretheyaffectionsofsomething
　　calledmind，which，asbeingthesubjectofthem，istherealego？Ifwe
　　saythisweimplythattheegoisanentity。Shallweassertthattheseimpressions
　　andideasarenotthemeresuperficialchangeswroughtonsomethinkingsubstance，
　　butarethemselvestheverybodyofthissubstance——areseverallythemodified
　　formswhichitfrommomenttomomentassumes？Thishypothesis，equallywith
　　theforegoing，impliesthattheconsciousselfexistsasapermanentcontinuous
　　being;sincemodificationsnecessarilyinvolvesomethingmodified。Shall
　　wethenbetakeourselvestothesceptic'sposition，andarguethatourimpressions
　　andideasthemselvesaretoustheonlyexistences，andthatthepersonality
　　saidtounderliethemisafiction？Wedonoteventhusescape;sincethis
　　proposition，verballyintelligiblebutreallyunthinkable，itselfmakesthe
　　assumptionwhichitprofessestorepudiate。Forhowcanconsciousnessbe
　　whollyresolvedintoimpressionsandideas，whenanimpressionofnecessity
　　implessomethingimpressed？Oragain，howcanthescepticwhohasdecomposed
　　hisconsciousnessintoimpressionsandideas，explainthefactthatheconsiders
　　themashisimpressionsandideas？Oroncemore，if，ashemust，headmits
　　thathehasanimpressionofhispersonalexistence，whatwarrantcanhe
　　showforrejectingthisimpressionasunrealwhileheacceptsallhisotherimpressionsasreal？Butnow，unavoidableasisthisbelief，itisyetabeliefadmittingof
　　nojustificationbyreason:nay，indeed，itisabeliefwhichreason，when
　　pressedforadistinctanswer，rejects。Oneofthemostrecentwriterswho
　　hastouchedonthisquestion——Mr。Mansel——does，indeed，contendthat
　　intheconsciousnessofselfwehaveapieceofrealknowledge。Hisposition
　　isthat"letsystemmakerssaywhattheywill，theunsophisticatedsense
　　ofmankindrefusestoacknowledgethatmindisbutabundleofstatesof
　　consciousness，asmatteris（possibly）abundleofsensiblequalities。"
　　ButthispositiondoesnotseemaconsistentoneforaKantist，whopays
　　butsmallrespectto"theunsophisticatedsenseofmankind"when
　　ittestifiestotheobjectivityofspace。Moreover，itmayreadilybeshown
　　thatacognitionofself，properlysocalled，isnegativedbythoselaws
　　ofthoughtwhichheemphasizes。Thefundamentalconditiontoallconsciousness，
　　insisteduponbyMr。ManselincommonwithSirWilliamHamiltonandothers，
　　istheantithesisofsubjectandobject。Onthis"primitivedualism
　　ofconsciousness，""fromwhichtheexplanationsofphilosophymust
　　taketheirstart，"Mr。ManselfoundshisrefutationoftheGermanabsolutists。
　　Butnowwhatisthecorollary，asbearingontheconsciousnessofself？The
　　mentalactinwhichselfisknownimplies，likeeveryothermentalact，a
　　perceivingsubjectandaperceivedobject。If，then，theobjectperceived
　　isself，whatisthesubjectthatperceives？orifitisthetrueselfwhich
　　thinks，whatotherselfcanitbethatisthoughtof？Clearly，atruecognition
　　ofselfimpliesastateinwhichtheknowingandtheknownareone——in
　　whichsubjectandobjectareidentified;andthisMr。Manselrightlyholdstobetheannihilationofboth。Sothatthepersonalityofwhicheachisconscious，andtheexistence
　　ofwhichistoeachafactbeyondallothersthemostcertain，isyetathingwhichcannotbeknownatall，inthestrictsenseoftheword。§21。UltimateScientificIdeas，then，areallrepresentativeofrealities
　　thatcannotbecomprehended。Afternomatterhowgreataprogressinthe
　　colligationoffactsandtheestablishmentofgeneralizationseverwider
　　andwider，thefundamentaltruthremainsasmuchbeyondreachasever。The
　　explanationofthatwhichisexplicable，doesbutbringintogreaterclearness
　　theinexplicablenessofthatwhichremainsbehind。Alikeintheexternal
　　andtheinternalworlds，themanofscienceseeshimselfinthemidstof
　　perpetualchangesofwhichhecandiscoverneitherthebeginningnorthe
　　end。IfheallowshimselftoentertainthehypothesisthattheUniverseoriginally
　　existedinadiffusedform，hefindsitimpossibletoconceivehowthiscame
　　tobeso;andequally，ifhespeculatesonthefuture，hecanassignnolimit
　　tothegrandsuccessionofphenomenaeverunfoldingthemselvesbeforehim。
　　Inlikemannerifhelooksinwardheperceivesthatbothendsofthethread
　　ofconsciousnessarebeyondhisgrasp。Neitherendcanberepresentedin
　　thought。When，again，heturnsfromthesuccessionofphenomena，external
　　orinternal，totheirintrinsicnature，heisjustasmuchatfault。Supposing
　　himineverycaseabletoresolvetheappearances，properties，andmovements
　　ofthings，intomanifestationsofForceinSpaceandTime;hestillfinds
　　thatForce，Space，andTimepassallunderstanding。Similarly，thoughanalysis
　　ofmentalactionsmayfinallybringhimdowntosensations，astheoriginal
　　materialsoutofwhichallthoughtiswoven，yetheislittleforwarder;
　　forhecangivenoaccounteitherofsensationsthemselvesorofthatwhich
　　isconsciousofsensations。Objectiveandsubjectivethingshethusascertains
　　tobealikeinscrutableintheirsubstanceandgenesis。Inalldirections
　　hisinvestigationseventuallybringhimfacetofacewithaninsolubleenigma;
　　andbeevermoreclearlyperceivesittobeaninsolubleenigma。Helearns
　　atoncethegreatnessandthelittlenessofthehumanintellect——itspower
　　indealingwithallthatcomeswithintherangeofexperience，itsimpotence
　　indealingwithallthattranscendsexperience。He，morethananyother，
　　trulyknowsthatinitsultimatenaturenothingcanbeknown。
　　Chapter4TheRelativityofallKnowledge§22。Thesameconclusionisthusarrivedatfromwhicheverpoint
　　wesetout。Ultimatereligiousideasandultimatescientificideas，aliketurnouttobemerelysymbolsoftheactual，notcognitionsofit。Theconviction，soreached，thathumanintelligenceisincapableofabsolute
　　knowledge，isonethathasbeenslowlygainingground。Eachnewontological
　　theory，propoundedinlieuofpreviousonesshowntobeuntenable，hasbeen
　　followedbyanewcriticismleadingtoanewscepticism。Allpossibleconceptions
　　havebeenonebyonetriedandfoundwanting;andsotheentirefieldof
　　speculationhasbeengraduallyexhaustedwithoutpositiveresult:theonly
　　resultreachedbeingthenegativeoneabovestated——thattherealityexisting
　　behindallappearancesis，andmusteverbe，unknown。Tothisconclusion
　　almosteverythinkerofnotehassubscribed。"Withtheexception，"
　　saysSirWilliamHamilton，"ofafewlateAbsolutisttheorizersinGermany，
　　thisis，perhaps，thetruthofallothersmostharmoniouslyre—echoedby
　　everyphilosopherofeveryschool。"Andamongthesehenames——Protagoras，
　　Aristotle，St。Augustin，Boethius，Averroes，AlbertusMagnus，Gerson，Leo
　　Hebraeus，Melancthon，Scaliger，FrancisPiccolomini，GiordanoBruno，Campanella，Bacon，Spinoza，Newton，Kant。Itremainstopointouthowthisbeliefmaybeestablishedrationally，
　　aswellasempirically。Notonlyisitthat，asintheearlierthinkersabove
　　named，avagueperceptionoftheinscrutablenessofthingsinthemselves
　　resultsfromdiscoveringtheillusivenessofsense—impressions;andnotonly
　　isitthat，asshownintheforegoingchapters，experimentsevolvealternative
　　impossibilitiesofthoughtoutofeveryfundamentalconception;butitis
　　thattherelativityofourknowledgemaybeprovedanalytically。Theinduction
　　drawnfromgeneralandspecialexperiences，maybeconfirmedbyadeduction
　　fromthenatureofourintelligence。Twowaysofreachingsuchadeduction
　　exist。Proofthatourcognitionsarenot，andnevercanbe，absolute，is
　　obtainablebyanalyzingeithertheproductorthought，ortheprocessofthought。Letusanalyzeeach。§23。If，whenwalkingthroughthefieldssomedayinSeptember，you
　　heararustleafewyardsinadvance，andonobservingtheditch—sidewhere
　　itoccurs，seetheherbageagitated，youwillprobablyturntowardsthespot
　　tolearnbywhatthissoundandmotionareproduced。Asyouapproachthere
　　fluttersintotheditchapartridge;onseeingwhichyourcuriosityissatisfied
　　——youhavewhatyoucallanexplanationoftheappearances。Theexplanation，
　　mark，amountstothis;thatwhereasthroughoutlifeyouhavehadcountless
　　experiencesofdisturbanceamongsmallstationarybodies，accompanyingthe
　　movementofotherbodiesamongthem，andhavegeneralizedtherelationbetween
　　suchdisturbancesandsuchmovements，youconsiderthisparticulardisturbance
　　explained，onfindingittopresentaninstanceofthelikerelation。Suppose
　　youcatchthepartridge;and，wishingtoascertainwhyitdidnotescape，
　　examineit，andfindatonespotatraceofbloodonitsfeathers。Younow
　　understand，asyousay，whathasdisabledthepartridge。Ithasbeenwounded
　　byasportsman——addsanothercasetothecasesalreadyseenbyyou，of
　　birdsbeingkilledorinjuredbytheshotdischargedatthemfromfowling—pieces。
　　Andinassimilatingthiscasetoothersuchcases，consistsyourunderstanding
　　ofit。Butnow，onconsideration，adifficultysuggestsitself。Onlyasingle
　　shothasstruckthepartridge，andthatnotinavitalplace:thewingsare
　　uninjured，asarealsothosemuscleswhichmovethem;andthecreatureproves
　　byitsstrugglesthatithasabundantstrength。Whythen，youinquireof
　　yourself，doesitnotfly？Occasionfavouring，youputthequestiontoan
　　anatomist，whofurnishesyouwithasolution。Hepointsoutthatthissolitary
　　shothaspassedclosetotheplaceatwhichthenervesupplyingthewing—muscles
　　ofoneside，divergesfromthespine;andexplainsthataslightinjuryto
　　thisnerve，extendingeventotheruptureofafewfibres，maybypreventing
　　aperfectco—ordinationintheactionsofthetwowings，destroythepower
　　offlight。Youarenolongerpuzzled。Butwhathashappened？——whathas
　　changedyourstatefromoneofperplexitytooneofcomprehension？Simply
　　thedisclosureofaclassofpreviouslyknowncases，alongwithwhichyou
　　canincludethiscase。Theconnexionbetweenlesionsofthenervoussystem
　　andparalysisoflimbshasbeenalreadymanytimesbroughtunderyournotice;andyouherefindarelationofcauseandeffectthatisessentiallysimilar。Letussupposeyouareledtoasktheanatomistquestionsaboutsomeorganic
　　actionswhich，remarkablethoughtheyare，youhadnotbeforecaredtounderstand。
　　Howisrespirationeffected？Youask——whydoesairperiodicallyrushinto
　　thelungs？Theansweristhatinfluxofairiscausedbyanenlargementof
　　thethoraciccavity，due，partlytodepressionofthediaphragm，partlyto
　　motionoftheribs。Buthowcanthesebonyhoopsmove，andhowdoesmotion
　　ofthemenlargethecavity？Inreplytheanatomistexplainsthatthoughattached
　　bytheirendstheribscanmovealittleroundtheirpointsofattachment;
　　hethenshowsyouthattheplaneofeachpairofribsmakesanacuteangle
　　withthespine;thatthisanglewidenswhenthesternalendsoftheribs
　　areraised;andhemakesyourealizetheconsequentdilatationofthecavity，
　　bypointingouthowtheareaofaparallelogramincreasesasitsanglesapproach
　　torightangles:youunderstandthisspecialfactwhenyouseeittobean
　　instanceofageneralgeometricalfact。Therestillarises，however，the
　　question——whydoestheairrushintothisenlargedcavity？Towhichcomes
　　theanswerthat，whenthethoraciccavityisenlarged，thecontainedair，
　　partiallyrelievedfrompressure，expands，andsolosessomeofitsresisting
　　Power;thathenceitopposestothepressureoftheexternalairalesspressure;
　　andthatasair，likeeveryotherfluid，pressesequallyinalldirections，
　　motionmustresultalonganylineinwhichtheresistanceislessthanelsewhere;
　　whencefollowsaninwardcurrent。Andthisinterpretationyourecognizeas
　　one，whenafewfactsoflikekind，exhibitedmoreplainlyinavisiblefluid
　　suchaswater，arecitedinillustration。Again，afterbeingshownthatthe
　　limbsarecompoundleversactinginessentiallythesamewayasleversof
　　iron，youwouldconsideryourselfashavingobtainedapartialrationale
　　ofanimalmovements。Thecontractionofamuscle，seemingbeforequiteunaccountable，
　　wouldseemlessunaccountablewereyoushownhow，byagalvaniccurrent，
　　aseriesofsoftironmagnetscouldbemadetoshortenitselfthroughthe
　　attractionofeachmagnetforitsneighbours:——anallegedanalogywhich
　　especiallyanswersthepurposeofourargument，since，whetherrealorfancied，
　　itequallyillustratesthementalilluminationthatresultsonfindinga
　　classofcaseswithinwhichaparticularcasemayperhapsbeincluded。Similarly
　　whenyoulearnthatanimalheatarisesfromchemicalcombination，andso
　　maybeclassedwithheatevolvedinotherchemicalcombinations——whenyou
　　learnthattheabsorptionofnutrientliquidsthroughthecoatsoftheintestines
　　isaninstanceofosmoticaction——whenyoulearnthatthechangesundergone
　　byfoodduringdigestion，arelikechangesartificiallyproducibleinthe
　　laboratory;youregardyourselfasknowingsomethingaboutthenaturesofthesephenomena。Observenowwhatwehavebeendoing。Webeganwithspecialandconcrete
　　facts。Inexplainingeach，andafterwardsexplainingthegeneralfactsof
　　whichtheyareinstances，wehavegotdowntocertainhighlygeneralfacts:
　　——toageometricalprinciple，toasimplelawofmechanicalaction，toa
　　lawoffluidequilibrium——totruthsinphysics，inchemistry，inthermology。
　　Theparticularphenomenawithwhichwesetouthavebeenmergedinlarger
　　andlargergroupsofphenomena;andastheyhavebeensomerged，wehave
　　arrivedatsolutionsweconsiderprofoundinproportionasthisprocesshas
　　beencarriedfar。Stilldeeperexplanationsaresimplyfurtherstepsinthe
　　samedirection。When，forinstance，itisaskedwhythelawofactionof
　　theleveriswhatitis，orwhyfluidequilibriumandfluidmotionexhibit
　　therelationstheydo，theanswerfurnishedbymathematiciansconsistsin
　　thedisclosureoftheprincipleofvirtualvelocities——aprincipleholding
　　truealikeinfluidsandsolids——aprincipleunderwhichtheothersarecomprehended。Isthisprocesslimitedorunlimited？Canwegoonforeverexplaining
　　classesoffactsbyincludingtheminlargerclasses;ormustweeventually
　　cometoalargestclass？Thesuppositionthattheprocessisunlimited，were
　　anyoneabsurdenoughtoespouseit，wouldstillimplythatanultimateexplanation
　　couldnotbereached，sinceinfinitetimewouldberequiredtoreachit。
　　Whiletheunavoidableconclusionthatitislimited，equallyimpliesthat
　　thedeepestfactcannotbeunderstood。Forifthesuccessivelydeeperinterpretations
　　ofNaturewhichconstituteadvancingknowledge，aremerelysuccessiveinclusions
　　ofspecialtruthsingeneraltruths，andofgeneraltruthsintruthsstill
　　moregeneral;itfollowsthatthemostgeneraltruth，notadmittingofinclusion
　　inanyother，doesnotadmitofinterpretation。Ofnecessity，therefore，
　　explanationmusteventuallybringusdowntotheinexplicable。Comprehension
　　mustbecomesomethingotherthancomprehension，beforetheultimatefactcanbecomprehended。§24。Theinferencewhichisthusforcedonuswhenweanalyzethe
　　productofthought，asexhibitedobjectivelyinscientificgeneralizations，
　　isequallyforcedonusbyananalysisoftheprocessofthought，asexhibited
　　subjectivelyinconsciousness。Thedemonstrationoftherelativecharacter
　　ofourknowledge，asdeducedfromthenatureofintelligence，hasbeenbrought
　　toitsmostdefiniteshapebySirWilliamHamilton。Icannotheredobetter
　　thanextractfromhisessayonthe"PhilosophyoftheUnconditioned，"thepassagecontainingthesubstanceofhisdoctrine。"Theunconditionallyunlimited，ortheInfinite，theunconditionally
　　limited，ortheAbsolute，cannotpositivelybeconstruedtothemind;they
　　canbeconceived，onlybyathinkingawayfrom，orabstractionof，those
　　veryconditionsunderwhichthoughtitselfisrealized;consequently，the
　　notionoftheUnconditionedisonlynegative，——negativeoftheconceivable
　　itself。Forexample，ontheonehandwecanpositivelyconceive，neither
　　anabsolutewhole，thatis，awholesogreat，thatwecannotalsoconceive
　　itasarelativepartofastillgreaterwhole;noranabsolutepart，that
　　is，apartsosmall，thatwecannotalsoconceiveitasarelativewhole，
　　divisibleintosmallerparts。Ontheotherhand，wecannotpositivelyrepresent，
　　orrealize，orconstruetothemind（ashereunderstandingandimagination
　　coincide），aninfinitewhole，forthiscouldonlybedonebytheinfinite
　　synthesisinthoughtoffinitewholes，whichwoulditselfrequireaninfinite
　　timeforitsaccomplishment;nor，forthesamereason，canwefollowout
　　inthoughtaninfinitedivisibilityofparts。Theresultisthesame，whetherweapplytheprocesstolimitationinspace，intime，orindegree。***"Astheconditionallylimited（whichwemaybrieflycalltheconditioned）
　　isthustheonlypossibleobjectofknowledgeandofpositivethought——
　　thoughtnecessarilysupposesconditions。Tothinkistocondition;andconditional
　　limitationisthefundamentallawofthepossibilityofthought。For，as
　　thegreyhoundcannotoutstriphisshadow，nor（byamoreappropriatesimile）
　　theeagleoutsoartheatmosphereinwhichhefloats，andbywhichalonehe
　　maybesupported;sothemindcannottranscendthatsphereoflimitation，
　　withinandthroughwhichexclusivelythepossibilityofthoughtisrealized。