InthetwoprecedinglecturesIhaveendeavouredtoindicatetoyoutheextentofthesubject—matteroftheinquiryuponwhichweareengaged；
　　andnow，havingthusacquiredsomeconceptionofthePastandPresentphenomenaofOrganicNature，Imustnowturntothatwhichconstitutesthegreatproblemwhichwehavesetbeforeourselves；——Imean，thequestionofwhatknowledgewehaveofthecausesofthesephenomenaoforganicnature，andhowsuchknowledgeisobtainable。
　　Here，onthethresholdoftheinquiry，anobjectionmeetsus。Thereareintheworldanumberofextremelyworthy，well—meaningpersons，whosejudgmentsandopinionsareentitledtotheutmostrespectonaccountoftheirsincerity，whoareofopinionthatVitalPhenomena，andespeciallyallquestionsrelatingtotheoriginofvitalphenomena，arequestionsquiteapartfromtheordinaryrunofinquiry，andare，bytheirverynature，placedoutofourreach。Theysaythatallthesephenomenaoriginatedmiraculously，orinsomewaytotallydifferentfromtheordinarycourseofnature，andthatthereforetheyconceiveittobefutile，nottosaypresumptuous，toattempttoinquireintothem。
　　Tosuchsincereandearnestpersons，Iwouldonlysay，thataquestionofthiskindisnottobeshelvedupontheoreticalorspeculativegrounds。YoumayrememberthestoryoftheSophistwhodemonstratedtoDiogenesinthemostcompleteandsatisfactorymannerthathecouldnotwalk；that，infact，allmotionwasanimpossibility；andthatDiogenesrefutedhimbysimplygettingupandwalkingroundhistub。So，inthesameway，themanofsciencerepliestoobjectionsofthiskind，bysimplygettingupandwalkingonward，andshowingwhatsciencehasdoneandisdoing——bypointingtothatimmensemassoffactswhichhavebeenascertainedandsystematizedundertheformsofthegreatdoctrinesofMorphology，ofDevelopment，ofDistribution，andthelike。Heseesanenormousmassoffactsandlawsrelatingtoorganicbeings，whichstandonthesamegoodsoundfoundationaseveryothernaturallaw；andtherefore，withthismassoffactsandlawsbeforeus，therefore，seeingthat，asfarasorganicmattershavehithertobeenaccessibleandstudied，theyhaveshownthemselvescapableofyieldingtoscientificinvestigation，wemayacceptthisasproofthatorderandlawreignthereaswellasintherestofnature；andthemanofsciencesaysnothingtoobjectorsofthissort，butsupposesthatwecanandshallwalktoaknowledgeoftheoriginoforganicnature，inthesamewaythatwehavewalkedtoaknowledgeofthelawsandprinciplesoftheinorganicworld。
　　Butthereareobjectorswhosaythesamefromignoranceandill—will。
　　TosuchIwouldreplythattheobjectioncomesillfromthem，andthattherealpresumption，Imayalmostsaytherealblasphemy，inthismatter，isintheattempttolimitthatinquiryintothecausesofphenomenawhichisthesourceofallhumanblessings，andfromwhichhassprungallhumanprosperityandprogress；for，afterall，wecanaccomplishcomparativelylittle；thelimitedrangeofourownfacultiesboundsusoneveryside，——thefieldofourpowersofobservationissmallenough，andhewhoendeavourstonarrowthesphereofourinquiriesisonlypursuingacoursethatislikelytoproducethegreatestharmtohisfellow—men。
　　Butnow，assuming，aswealldo，Ihope，thatthesephenomenaareproperlyaccessibletoinquiry，andsettingoutuponoursearchintothecausesofthephenomenaoforganicnature，or，atanyrate，settingouttodiscoverhowmuchweatpresentknowupontheseabstrusematters，thequestionarisesastowhatistobeourcourseofproceeding，andwhatmethodwemustlaydownforourguidance。Ireplytothatquestion，thatourmethodmustbeexactlythesameasthatwhichispursuedinanyotherscientificinquiry，themethodofscientificinvestigationbeingthesameforallordersoffactsandphenomenawhatsoever。
　　Imustdwellalittleonthispoint，forIwishyoutoleavethisroomwithaveryclearconvictionthatscientificinvestigationisnot，asmanypeopleseemtosuppose，somekindofmodernblackart。Isaythatyoumighteasilygatherthisimpressionfromthemannerinwhichmanypersonsspeakofscientificinquiry，ortalkaboutinductiveanddeductivephilosophy，ortheprinciplesofthe"Baconianphilosophy。"I
　　doprotestthat，ofthevastnumberofcantsinthisworld，therearenone，tomymind，socontemptibleasthepseudoscientificcantwhichistalkedaboutthe"Baconianphilosophy。"
　　TohearpeopletalkaboutthegreatChancellor——andaverygreatmanhecertainlywas，——youwouldthinkthatitwashewhohadinventedscience，andthattherewasnosuchthingassoundreasoningbeforethetimeofQueenElizabeth。Ofcourseyousay，thatcannotpossiblybetrue；youperceive，onamoment’sreflection，thatsuchanideaisabsurdlywrong，andyet，sofirmlyrootedisthissortofimpression，——Icannotcallitanidea，orconception，——thethingistooabsurdtobeentertained，——butsocompletelydoesitexistatthebottomofmostmen’sminds，thatthishasbeenamatterofobservationwithmeformanyyearspast。Therearemanymenwho，thoughknowingabsolutelynothingofthesubjectwithwhichtheymaybedealing，wish，nevertheless，todamagetheauthorofsomeviewwithwhichtheythinkfittodisagree。Whattheydo，then，isnottogoandlearnsomethingaboutthesubject，whichonewouldnaturallythinkthebestwayoffairlydealingwithit；buttheyabusetheoriginatoroftheviewtheyquestion，inageneralmanner，andwindupbysayingthat，"Afterall，youknow，theprinciplesandmethodofthisauthoraretotallyopposedtothecanonsoftheBaconianphilosophy。"Theneverybodyapplauds，asamatterofcourse，andagreesthatitmustbeso。Butifyouweretostopthemallinthemiddleoftheirapplause，youwouldprobablyfindthatneitherthespeakernorhisapplauderscouldtellyouhoworinwhatwayitwasso；neithertheonenortheotherhavingtheslightestideaofwhattheymeanwhentheyspeakofthe"Baconianphilosophy。"
　　Youwillunderstand，Ihope，thatIhavenottheslightestdesiretojoinintheoutcryagainsteitherthemorals，theintellect，orthegreatgeniusofLordChancellorBacon。Hewasundoubtedlyaverygreatman，letpeoplesaywhattheywillofhim；butnotwithstandingallthathedidforphilosophy，itwouldbeentirelywrongtosupposethatthemethodsofmodernscientificinquiryoriginatedwithhim，orwithhisage；theyoriginatedwiththefirstman，whoeverhewas；andindeedexistedlongbeforehim，formanyoftheessentialprocessesofreasoningareexertedbythehigherorderofbrutesascompletelyandeffectivelyasbyourselves。Weseeinmanyofthebrutecreationtheexerciseofone，atleast，ofthesamepowersofreasoningasthatwhichweourselvesemploy。
　　Themethodofscientificinvestigationisnothingbuttheexpressionofthenecessarymodeofworkingofthehumanmind。Itissimplythemodeatwhichallphenomenaarereasonedabout，renderedpreciseandexact。
　　Thereisnomoredifference，butthereisjustthesamekindofdifference，betweenthementaloperationsofamanofscienceandthoseofanordinaryperson，asthereisbetweentheoperationsandmethodsofabakerorofabutcherweighingouthisgoodsincommonscales，andtheoperationsofachemistinperformingadifficultandcomplexanalysisbymeansofhisbalanceandfinely—graduatedweights。Itisnotthattheactionofthescalesintheonecase，andthebalanceintheother，differintheprinciplesoftheirconstructionormannerofworking；butthebeamofoneissetonaninfinitelyfineraxisthantheother，andofcourseturnsbytheadditionofamuchsmallerweight。
　　Youwillunderstandthisbetter，perhaps，ifIgiveyousomefamiliarexample。Youhaveallhearditrepeated，Idaresay，thatmenofscienceworkbymeansofInductionandDeduction，andthatbythehelpoftheseoperations，they，inasortofsense，wringfromNaturecertainotherthings，whicharecalledNaturalLaws，andCauses，andthatoutofthese，bysomecunningskilloftheirown，theybuildupHypothesesandTheories。Anditisimaginedbymany，thattheoperationsofthecommonmindcanbebynomeanscomparedwiththeseprocesses，andthattheyhavetobeacquiredbyasortofspecialapprenticeshiptothecraft。Tohearalltheselargewords，youwouldthinkthatthemindofamanofsciencemustbeconstituteddifferentlyfromthatofhisfellowmen；butifyouwillnotbefrightenedbyterms，youwilldiscoverthatyouarequitewrong，andthatalltheseterribleapparatusarebeingusedbyyourselveseverydayandeveryhourofyourlives。
　　Thereisawell—knownincidentinoneofMoliere’splays，wheretheauthormakestheheroexpressunboundeddelightonbeingtoldthathehadbeentalkingproseduringthewholeofhislife。Inthesameway，Itrust，thatyouwilltakecomfort，andbedelightedwithyourselves，onthediscoverythatyouhavebeenactingontheprinciplesofinductiveanddeductivephilosophyduringthesameperiod。Probablythereisnotoneherewhohasnotinthecourseofthedayhadoccasiontosetinmotionacomplextrainofreasoning，oftheverysamekind，thoughdifferingofcourseindegree，asthatwhichascientificmangoesthroughintracingthecausesofnaturalphenomena。
　　Averytrivialcircumstancewillservetoexemplifythis。Supposeyougointoafruiterer’sshop，wantinganapple，——youtakeupone，and，onbitingit，youfinditissour；youlookatit，andseethatitishardandgreen。Youtakeupanotherone，andthattooishard，green，andsour。Theshopmanoffersyouathird；but，beforebitingit，youexamineit，andfindthatitishardandgreen，andyouimmediatelysaythatyouwillnothaveit，asitmustbesour，likethosethatyouhavealreadytried。
　　Nothingcanbemoresimplethanthat，youthink；butifyouwilltakethetroubletoanalyzeandtraceoutintoitslogicalelementswhathasbeendonebythemind，youwillbegreatlysurprised。Inthefirstplace，youhaveperformedtheoperationofInduction。Youfoundthat，intwoexperiences，hardnessandgreennessinapplesgotogetherwithsourness。Itwassointhefirstcase，anditwasconfirmedbythesecond。True，itisaverysmallbasis，butstillitisenoughtomakeaninductionfrom；yougeneralizethefacts，andyouexpecttofindsournessinappleswhereyougethardnessandgreenness。Youfounduponthatagenerallaw，thatallhardandgreenapplesaresour；andthat，sofarasitgoes，isaperfectinduction。Well，havinggotyournaturallawinthisway，whenyouareofferedanotherapplewhichyoufindishardandgreen，yousay，"Allhardandgreenapplesaresour；
　　thisappleishardandgreen，thereforethisappleissour。"Thattrainofreasoningiswhatlogicianscallasyllogism，andhasallitsvariouspartsandterms，——itsmajorpremiss，itsminorpremiss，anditsconclusion。And，bythehelpoffurtherreasoning，which，ifdrawnout，wouldhavetobeexhibitedintwoorthreeothersyllogisms，youarriveatyourfinaldetermination，"Iwillnothavethatapple。"Sothat，yousee，youhave，inthefirstplace，establishedalawbyInduction，anduponthatyouhavefoundedaDeduction，andreasonedoutthespecialconclusionoftheparticularcase。Wellnow，suppose，havinggotyourlaw，thatatsometimeafterwards，youarediscussingthequalitiesofappleswithafriend：youwillsaytohim，"Itisaverycuriousthing，——butIfindthatallhardandgreenapplesaresour！"Yourfriendsaystoyou，"Buthowdoyouknowthat？"Youatoncereply，"Oh，becauseIhavetrieditoverandoveragain，andhavealwaysfoundthemtobeso。"Well。ifweweretalkingscienceinsteadofcommonsense，weshouldcallthatanExperimentalVerification。And，ifstillopposed，yougofurther，andsay，"IhaveheardfromthepeopleinSomersetshireandDevonshire，wherealargenumberofapplesaregrown，thattheyhaveobservedthesamething。ItisalsofoundtobethecaseinNormandy，andinNorthAmerica。Inshort，Ifindittobetheuniversalexperienceofmankindwhereverattentionhasbeendirectedtothesubject。"Whereupon，yourfriend，unlessheisaveryunreasonableman，agreeswithyou，andisconvincedthatyouarequiterightintheconclusionyouhavedrawn。Hebelieves，althoughperhapshedoesnotknowhebelievesit，thatthemoreextensiveVerificationsare，——thatthemorefrequentlyexperimentshavebeenmade，andresultsofthesamekindarrivedat，——thatthemorevariedtheconditionsunderwhichthesameresultshavebeenattained，themorecertainistheultimateconclusion，andhedisputesthequestionnofurther。Heseesthattheexperimenthasbeentriedunderallsortsofconditions，astotime，place，andpeople，withthesameresult；andhesayswithyou，therefore，thatthelawyouhavelaiddownmustbeagoodone，andhemustbelieveit。
　　Insciencewedothesamething；——thephilosopherexercisespreciselythesamefaculties，thoughinamuchmoredelicatemanner。Inscientificinquiryitbecomesamatterofdutytoexposeasupposedlawtoeverypossiblekindofverification，andtotakecare，moreover，thatthisisdoneintentionally，andnotlefttoamereaccident，asinthecaseoftheapples。Andinscience，asincommonlife，ourconfidenceinalawisinexactproportiontotheabsenceofvariationintheresultofourexperimentalverifications。Forinstance，ifyouletgoyourgraspofanarticleyoumayhaveinyourhand，itwillimmediatelyfalltotheground。Thatisaverycommonverificationofoneofthebestestablishedlawsofnature——thatofgravitation。Themethodbywhichmenofscienceestablishtheexistenceofthatlawisexactlythesameasthatbywhichwehaveestablishedthetrivialpropositionaboutthesournessofhardandgreenapples。Butwebelieveitinsuchanextensive，thorough，andunhesitatingmannerbecausetheuniversalexperienceofmankindverifiesit，andwecanverifyitourselvesatanytime；andthatisthestrongestpossiblefoundationonwhichanynaturallawcanrest。
　　Somuchbywayofproofthatthemethodofestablishinglawsinscienceisexactlythesameasthatpursuedincommonlife。Letusnowturntoanothermatter（thoughreallyitisbutanotherphaseofthesamequestion），andthatis，themethodbywhich，fromtherelationsofcertainphenomena，weprovethatsomestandinthepositionofcausestowardstheothers。
　　Iwanttoputthecaseclearlybeforeyou，andIwillthereforeshowyouwhatImeanbyanotherfamiliarexample。Iwillsupposethatoneofyou，oncomingdowninthemorningtotheparlourofyourhouse，findsthatatea—potandsomespoonswhichhadbeenleftintheroomonthepreviouseveningaregone，——thewindowisopen，andyouobservethemarkofadirtyhandonthewindow—frame，andperhaps，inadditiontothat，younoticetheimpressofahob—nailedshoeonthegraveloutside。Allthesephenomenahavestruckyourattentioninstantly，andbeforetwominuteshavepassedyousay，"Oh，somebodyhasbrokenopenthewindow，enteredtheroom，andrunoffwiththespoonsandthetea—pot！"Thatspeechisoutofyourmouthinamoment。Andyouwillprobablyadd，"I
　　knowtherehas；Iamquitesureofit！"Youmeantosayexactlywhatyouknow；butinrealitywhatyouhavesaidhasbeentheexpressionofwhatis，inallessentialparticulars，anHypothesis。Youdonot’know’
　　itatall；itisnothingbutanhypothesisrapidlyframedinyourownmind！Anditisanhypothesisfoundedonalongtrainofinductionsanddeductions。
　　Whatarethoseinductionsanddeductions，andhowhaveyougotatthishypothesis？Youhaveobserved，inthefirstplace，thatthewindowisopen；butbyatrainofreasoninginvolvingmanyInductionsandDeductions，youhaveprobablyarrivedlongbeforeattheGeneralLaw——andaverygoodoneitis——thatwindowsdonotopenofthemselves；
　　andyouthereforeconcludethatsomethinghasopenedthewindow。A
　　secondgenerallawthatyouhavearrivedatinthesamewayis，thattea—potsandspoonsdonotgooutofawindowspontaneously，andyouaresatisfiedthat，astheyarenotnowwhereyouleftthem，theyhavebeenremoved。Inthethirdplace，youlookatthemarksonthewindow—sill，andtheshoemarksoutside，andyousaythatinallpreviousexperiencetheformerkindofmarkhasneverbeenproducedbyanythingelsebutthehandofahumanbeing；andthesameexperienceshowsthatnootheranimalbutmanatpresentwearsshoeswithhob—nailsonthemsuchaswouldproducethemarksinthegravel。Idonotknow，evenifwecoulddiscoveranyofthose"missinglinks"thataretalkedabout，thattheywouldhelpustoanyotherconclusion！Atanyratethelawwhichstatesourpresentexperienceisstrongenoughformypresentpurpose。——Younextreachtheconclusion，thatasthesekindsofmarkshavenotbeenleftbyanyotheranimalsthanmen，orareliabletobeformedinanyotherwaythanbyaman’shandandshoe，themarksinquestionhavebeenformedbyamaninthatway。Youhave，further，agenerallaw，foundedonobservationandexperience，andthat，too，is，Iamsorrytosay，averyuniversalandunimpeachableone，——thatsomemenarethieves；andyouassumeatoncefromallthesepremisses——andthatiswhatconstitutesyourhypothesis——thatthemanwhomadethemarksoutsideandonthewindow—sill，openedthewindow，gotintotheroom，andstoleyourtea—potandspoons。Youhavenowarrivedata’VeraCausa’；——youhaveassumedaCausewhichitisplainiscompetenttoproduceallthephenomenayouhaveobserved。Youcanexplainallthesephenomenaonlybythehypothesisofathief。Butthatisahypotheticalconclusion，ofthejusticeofwhichyouhavenoabsoluteproofatall；itisonlyrenderedhighlyprobablebyaseriesofinductiveanddeductivereasonings。
　　Isupposeyourfirstaction，assumingthatyouareamanofordinarycommonsense，andthatyouhaveestablishedthishypothesistoyourownsatisfaction，willverylikelybetogooffforthepolice，andsetthemonthetrackoftheburglar，withtheviewtotherecoveryofyourproperty。Butjustasyouarestartingwiththisobject，somepersoncomesin，andonlearningwhatyouareabout，says，"Mygoodfriend，youaregoingonagreatdealtoofast。Howdoyouknowthatthemanwhoreallymadethemarkstookthespoons？Itmighthavebeenamonkeythattookthem，andthemanmayhavemerelylookedinafterwards。"Youwouldprobablyreply，"Well，thatisallverywell，butyouseeitiscontrarytoallexperienceofthewaytea—potsandspoonsareabstracted；sothat，atanyrate，yourhypothesisislessprobablethanmine。"Whileyouaretalkingthethingoverinthisway，anotherfriendarrives，oneofthatgoodkindofpeoplethatIwastalkingofalittlewhileago。Andhemightsay，"Oh，mydearsir，youarecertainlygoingonagreatdealtoofast。Youaremostpresumptuous。Youadmitthatalltheseoccurrencestookplacewhenyouwerefastasleep，atatimewhenyoucouldnotpossiblyhaveknownanythingaboutwhatwastakingplace。HowdoyouknowthatthelawsofNaturearenotsuspendedduringthenight？Itmaybethattherehasbeensomekindofsupernaturalinterferenceinthiscase。"Inpointoffact，hedeclaresthatyourhypothesisisoneofwhichyoucannotatalldemonstratethetruth，andthatyouarebynomeanssurethatthelawsofNaturearethesamewhenyouareasleepaswhenyouareawake。
　　Well，now，youcannotatthemomentanswerthatkindofreasoning。Youfeelthatyourworthyfriendhasyousomewhatatadisadvantage。Youwillfeelperfectlyconvincedinyourownmind，however，thatyouarequiteright，andyousaytohim，"Mygoodfriend，Icanonlybeguidedbythenaturalprobabilitiesofthecase，andifyouwillbekindenoughtostandasideandpermitmetopass，Iwillgoandfetchthepolice。"
　　Well，wewillsupposethatyourjourneyissuccessful，andthatbygoodluckyoumeetwithapoliceman；thateventuallytheburglarisfoundwithyourpropertyonhisperson，andthemarkscorrespondtohishandandtohisboots。Probablyanyjurywouldconsiderthosefactsaverygoodexperimentalverificationofyourhypothesis，touchingthecauseoftheabnormalphenomenaobservedinyourparlour，andwouldactaccordingly。
　　Now，inthissuppositiouscase，Ihavetakenphenomenaofaverycommonkind，inorderthatyoumightseewhatarethedifferentstepsinanordinaryprocessofreasoning，ifyouwillonlytakethetroubletoanalyseitcarefully。AlltheoperationsIhavedescribed，youwillsee，areinvolvedinthemindofanymanofsenseinleadinghimtoaconclusionastothecourseheshouldtakeinordertomakegoodarobberyandpunishtheoffender。Isaythatyouareled，inthatcase，toyourconclusionbyexactlythesametrainofreasoningasthatwhichamanofsciencepursueswhenheisendeavouringtodiscovertheoriginandlawsofthemostoccultphenomena。Theprocessis，andalwaysmustbe，thesame；andpreciselythesamemodeofreasoningwasemployedbyNewtonandLaplaceintheirendeavourstodiscoveranddefinethecausesofthemovementsoftheheavenlybodies，asyou，withyourowncommonsense，wouldemploytodetectaburglar。Theonlydifferenceis，thatthenatureoftheinquirybeingmoreabstruse，everystephastobemostcarefullywatched，sothattheremaynotbeasinglecrackorflawinyourhypothesis。Aflaworcrackinmanyofthehypothesesofdailylifemaybeoflittleornomomentasaffectingthegeneralcorrectnessoftheconclusionsatwhichwemayarrive；but，inascientificinquiry，afallacy，greatorsmall，isalwaysofimportance，andissuretobeconstantlyproductiveofmischievous，ifnotfatalresults。