Letusbeginbyconsideringatheory，primarilypsychological，whichhasatleastthemeritofantiquity——asitisadmittedlyderivedfromAristotle，——andis，insomeformorother，stillcurrent。ItisthatexpressedbySirW。
　　Hamiltoninthefollowingpropositions:``Pleasureisthereflexofthespontaneousandunimpededexertionofapowerofwhoseenergyweareconscious:
　　pain，areflexoftheover-strainedorrepressedexertionofsuchapower。’’
　　Thephrasessuggestactiveasordinarilydistinguishedfrompassivestates；butHamiltonexplainsthat``energy’’andsimilarterms``aretobeunderstoodtodenoteindifferentlyalltheprocessesofourhigherandlowerlifeofwhichweareconscious’’，——onthegroundthatconsciousnessitselfimpliesmorethanamerepassivityofthesubject。Ithink，however，thatthetheoryisevidentlyframedprimarilytosuitthepleasuresandpainsthatbelongtotheintellectuallifeassuch，andisonlyappliedbyasomewhatviolentstrainingtoanimportantclassamongthepleasuresandpainsthatbelongtoman’sanimallife。ForHamiltonexplainshistermsa``spontaneous’’andb``unimpeded’’toimplyrespectivelyaabsenceof``forciblerepression’’or``forciblestimulation’’ofthepowerexercised，andbabsenceofchecksorhindrancesonthepartoftheobjectaboutwhichitisconversant。Butthesetermsseemtohavenoclearpsychicalimportinapplicationtoorganicsensationsofthekindordinarilycalledpassive。E。g。thefeelingsandvaguerepresentationsofbodilyprocesseswhichconstitutetheconsciousnessofatoothacheareasfreefromconsciousrepressionorstimulationasthosewhichconstitutetheconsciousnessthataccompaniesawarmbath:——exceptsofarasthemerepresenceofpainimpliesconstraint，sinceweexperienceitunwillingly，andthemerepresenceofpleasureimpliestheopposite:butinthissenseconstraintanditsoppositearecharacteristicsoftheeffectstobeexplained，andcannotthereforeberegardedastheircauses。
　　Indeed，theethicalinterestandvalueofthetheoryappearstometolieinitsveryone-sidedness。
　　Ittendstocorrectavulgarerrorintheestimateofpleasure，bydirectingattentionstronglytotheimportanceofaclassofpleasureswhichordinarypleasure-seekingprobablyundervalues，——thepleasuresthatspeciallybelongtoalifefilledwithstrenuousactivity，whetherpurelyintellectual，orpracticalandpartlyphysical。Inthesamewayiteffectivelydispelsthepopularinadvertenceofregardinglabourasnormallypainfulbecausesomelabourisso，andbecausethepleasuresconnectedwithrelieffromtoil——thepleasuresofreposeandplay——areintheexperienceofmostpersonsmorestrikingthanthepleasuresofstrenuousactivity。Atthesametime，evenifwelimitthetheorytothepleasuresandpainsimmediatelyconnectedwithvoluntaryactivity——intellectualorphysical——itseemstomedevoidnotonlyofdefiniteguidance，butalsoofadequatetheoreticalprecision。Foritseemstoimplythattheexerciseofourpowersisalwaysmadelesspleasantbythepresenceofimpediments；butthisisobviouslynottrueeitherofmainlyintellectualormainlyphysicalactivities。Someobstaclesundeniablyincreasepleasurebydrawingoutforceandskilltoovercomethem，asisclearlyshowninthecaseofgamesandsports:andevenifweunderstandpain-causingimpedimentstobeonlysuchhindrancesasrepressanddiminishaction，Idonotfindthatthetheoryissupportedbyexperience，exceptsofarastherepressioncausesthespecificdiscomfortofunsatisfieddesire。E。g。Ifindentertainmentratherthandiscomfortintryingtomakeoutobjectsinadimlight，orthemeaningofaspeechinastrangelanguage，providedthatfailuredoesnotinterferewiththeattainmentofanyendtowhichIattachimportance。ItisafundamentaldefectinHamilton’stheory，eveninitsmorelimitedapplication，thatitignorestheteleologicalcharacterofnormalhumanactivity。
　　Thisdefectisavoidedinamodificationofthetheorythatarecentwriterhasadopted。``Theantithesis’’，saysMr。Stout，``betweenpleasureandpainiscoincidentwiththeantithesisbetweenfreeandimpededprogresstowardsanend。Unimpededprogressispleasantinproportiontotheintensityandcomplexityofmentalexcitement。
　　Anactivitywhichis？thwartedandretarded？ispainfulinproportiontoitsintensityandcomplexityandtothedegreeofthehindrance。’’Mr。
　　Stoutadmitsthedifficultyofapplyingthisprincipleofexplanationtothepleasuresandpainsofsense:[5]and——unlikeHamilton——heexpresslyrecognisesthat``astrugglewithdifficultieswhichisnottooprolongedortoointensemayenhancethepleasureofsuccessoutofallproportiontoitsownpainfulness。’’Butthisqualificationseemstorenderthepropositionsfirstlaiddownunimportantfromourpresentpracticalpointofview，whatevermaybetheirtheoreticalvalue。Ithink，too，thattheimportanceofantecedentdesire，asaconditionofthepleasuresandpainsattendantonvoluntaryactivities，shouldbemoreexpresslyrecognised。
　　Whendesireisstrong，hopefulefforttoovercomedifficultiesinthewayoffruitiontendstobeproportionallypleasurable——apartfromactualsuccess——whiledisappointmentorthefearofdisappointmentsimilarlytendstobepainful:butwhendesireisnotstrong，theshockofthwartedactivityandunfulfilledexpectationmayberatheragreeablethanotherwise。
　　Thus，supposeItakeawalkforpleasure，intendingtoreachaneighbouringvillage，andfindanunexpectedfloodcrossingmyroad；ifIhavenostrongmotiveforarrivingatthevillage，thesurpriseandconsequentchangeintheplanofmywalkwillprobablybeonthewholeapleasurableincident。
　　Theimportanceofeagerdesireasaconditionofpleasureisnoteworthyfromanethicalpointofview:asitgivesthepsychologicalbasisforthefamiliarprecepttorepress——withaviewtoprivatehappiness——desiresforendsthatareeitherunattainableorincompatiblewiththecourseoflifewhichprudencemarksout；andforthesomewhatlesstritemaximofencouraginganddevelopingdesiresthatpromptinthesamedirectionasrationalchoice。
　　Supposenowwedropthedubiousterm``unimpeded’’——retainingHamilton’sideaof``overstrainedorrepressedexertion’’astheconditionofpain——andatthesametimepassingtoaphysicalpointofview，meanby``activity’’
　　theactivityofanorgan。WethusreachwhatissubstantiallyMr。
　　Spencer’sdoctrine，thatpainsarethepsychicalconcomitantsofexcessiveordeficientactionsoforgans，whilepleasuresaretheconcomitantsofmediumactivities。Inconsideringthistheoryitwillbeconvenienttotakepainsandpleasuresseparately:asitisobviouslybasedprimarilyonexperiencesofpainratherthanofpleasure，——especiallyofthepainsofsensetowhichHamilton’stheoryseemedpalpablyinapplicable。Instancesareabundantinwhichpainisobviouslycausedbyexcessivestimulationofnerves。Thuswhenwegraduallyincreasetheintensityofsensibleheat，pressure，musculareffort，weencounterpainatacertainpointoftheincrease；``deafening’’soundsarehighlydisagreeable；andtoconfrontatropicalsunwithunprotectedeyeballswouldsoonbecometorture。Somepains，again，asSpencerpointsout，arisefromtheexcessiveactionsoforganswhosenormalactionsyieldnofeelings:aswhenthedigestiveapparatusisovertaxed。Stillinnoneofthesecasesdoesitseemclearthatpainsupervenesthroughamereintensificationindegreeoftheactionoftheorganinquestion；andnotratherthroughsomechangeinthekindofaction——someinchoatedisintegrationordisorganisation。Andthislattercause——ratherthanmerequantityofstimulation——isstronglysuggestedbyaconsiderationofthepainsduetowoundsanddiseases，andevenofthetransientdigestivediscomfortswhicharisefromanimproperkindratherthananimproperquantityoffood。Andasimilarexplanationseemstomemostprobableinthecaseofpainswhich，accordingtoMr。Spencer，arisefrom``deficient’’action。Hespeaksoftheseas``discomfortsorcravings’’
　　but，asIhavebeforepointedout，bodilyappetitesandotherdesiresmaybestrongly-feltimpulsestoactionwithoutbeingappreciablypainful:
　　and，inmyexperience，whentheybecomedecidedlypainful，somedisturbancetendingtoderangementmaybepresumedeitherintheorganprimarilyconcernedorintheorganismasawhole。Thushunger，inmyexperience，maybeextremelykeenwithoutbeingappreciablypainful:andwhenIfinditpainful，experienceleadsmetoexpectatemporarilyreducedpowerofassimilation，indicatingsomedisorganisationinthedigestiveapparatus。[9]
　　Inanycase，empiricalevidencesupports``excessiveaction’’ofanorganasacauseofpainfarmoreclearlythan``deficientaction’’。Indeedaconsiderationofthisevidencehasledsomepsychologiststoadoptthegeneralisationthatthereisnoqualityofsensationabsolutelypleasantorunpleasant，butthateverykindofsensationasitgrowsinintensitybeginsatacertainpointtobepleasurable，andcontinuessuchuptoacertainfurtherpointatwhichitpassesrapidlythroughindifferenceintopain。Myownexperience，however，failstosupportthisgeneralisation。IagreewithGurneythat``ofmanytastesandodoursthefaintestpossiblesuggestionisdisagreeable’’；
　　whileotherfeelingsresultingfromstimulationofsense-organsappeartoremainhighlypleasurableatthehighestdegreeofstimulationwhichtheactualconditionsofphysicallifeappeartoallow。
　　Howeverthismaybe，whetherweconceivethenervousactionofwhichpainisanimmediateconsequentorconcomitantasmerelyexcessiveinquantity，orinsomewaydiscordantordisorganisedinquality，itisobviousthatneitherexplanationcanfurnishuswithanyimportantpracticalguidance:sincewehavenogeneralmeansofascertaining，independentlyofourexperienceofpainitself，whatnervousactionsareexcessiveordisorganised:andthecaseswherewehavesuchmeansdonotpresentanypracticalproblemswhichthetheoryenablesustosolve。Noonedoubtsthatwoundsanddiseasesaretobeavoidedunderallordinarycircumstances:
　　andintheexceptionalcircumstancesinwhichwemaybemovedtochoosethemastheleastofseveralevils，theexactestknowledgeoftheirpreciseoperationincausingpainisnotlikelytoassistourchoice。
　　Itmaybesaid，however，——turningfrompaintopleasure，——thatthegeneralisationwhichwehavebeenconsideringatanyrategivesusapsychophysicalbasisfortheancientmaximof``avoidingexcess’’inthepursuitofpleasure。Butwehavetoobservethatthepracticalneedofthismaximislargelyduetothequalificationswhichthepsychophysicalgeneralisationrequirestomakeittrue。Thusitisespeciallyneededintheimportantcasesinwhichover-stimulationisfollowedbypainnotatoncebutafteranintervalofvaryinglength。E。g。alcoholicdrinking，tomany，remainspleasurableatthetimeuptothepointofexcessatwhichthebraincannolongerperformitsfunctions:itis``nextmorning’’thatthepaincomes，orperhaps——inthecaseof``well-seasoned’’topers——nottillaftermanyyearsofhabitualexcess。Itshouldbenotedalsothatitisnotalwaystheorganofwhichtheexercisegivespleasurethatalso，throughover-exercise，causesthepainofexcess。Thuswhenwearetemptedtoeattoomuch，theseductivepleasureismainlyduetothenervesoftastewhicharenotovertaxed；thepainscomefromtheorgansofdigestion，whosefaint，vaguepleasuresalonewouldhardlytemptthevoluptuarytoexcess。Inthecaseofdangerousmentalexcitementsthepenaltyonexcessisusuallystillmoreindirect。
　　Onthewhole，grantingthatpleasurelikevirtueresidessomewhereinthemean，itmustbeadmittedthatthispropositiongivesnopracticaldirectionsforattainingit。Forfirst，grantingthatbothexcessiveanddeficientactivitiesoforganscausepain，thequestionstillremains——asSpencerhimselfsays——Whatdeterminesinanycasethelowerandthehigherlimitswithinwhichactionispleasurable？Spencer’sanswertothisquestionIwillconsiderpresently。
　　Butthereisaquestionnolessobvioustowhichhedoesnotexpresslyadvert，viz。whyamongthenormalactivitiesofourphysicalorgans，thathavecounterpartsinconsciousness，someonlyarepleasurableinanyappreciabledegree，whilemanyifnotmostarenearlyorquiteindifferent。Itseemsundeniablee。g。thatwhiletastesandsmellsaremostlyeitheragreeableordisagreeable，mostsensationsoftouchandmanyofsightandsoundarenotappreciablyeither；andthat，inthedailyroutineofhealthylife，eatinganddrinkingareordinarilypleasant，whiledressingandundressing，walkingandmuscularmovementsgenerallyarepracticallyindifferent。