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。