Itdoesnotseemthatanadequateexplanationcanbefoundintheoperationofhabit。Itisnodoubttruethatactionsthroughfrequentuniformrepetitiontendtobecomeautomaticandlosetheirconsciouscounterparts，andhedonicindifferencecertainlyseemsinsomecasestobeastagethroughwhichsuchactionspassonthewaytounconsciousness。Thusevenabusinesswalkinastrangetownisnormallypleasantthroughthenoveltyofthesights:butasimilarwalkinthetownwhereonelivesisordinarilyindifferent，ornearlyso；whileifone’sattentionisstronglyabsorbedbythebusiness，itmaybeperformedtoagreatextentunconsciously。Ontheotherhand，theoperationsofhabitoftenhavetheoppositeeffectofmakingactivitiespleasantwhichwereatfirstindifferentorevendisagreeable:asinthecaseofacquiredtastes，physicalorintellectual。Indeedsuchexperienceshavelongbeen——Ithink，quitelegitimately——usedbymoralistsasanencouragementtoirksomeduties，onthegroundthattheirirksomenesswillbetransient，throughtheoperationofhabit，whilethegainoftheirperformancewillbepermanent。Mr。Spencer，indeed，regardssuchexperiencesassoimportantthatheventurestobaseonthemthepredictionthat``pleasurewilleventuallyaccompanyeverymodeofactiondemandedbysocialconditions’’。This，however，seemsundulyoptimistic，inviewnotonlyofthefirst-mentionedtendencyofhabittohedonicindifference，butalsoofathirdtendencytorenderactions，atfirstindifferentorevenpleasant，graduallymoreirksome。Thusourintellectgraduallyweariesofmonotonousactivities，andtheennuimaysometimesbecomeintense:soagaintherelishofakindofdietatfirstagreeablemayturnthroughmonotonyintodisgust。
Somequitedifferentexplanationmustthereforebesoughtforthevaryingdegreesinwhichpleasureaccompaniesnormalactivities。CanwefindthisinasuggestionofMr。Spencer’s，developedbyMr。GrantAllen，thatthepleasurablenessofnormalorganicactivitiesdependsontheirintermittence，andthat``theamountofpleasureisprobably？intheinverseratioofthenaturalfrequencyofexcitation’’
ofthenerve-fibresinvolved？Thistheorycertainlyfindssomesupportinthefactthatthesensualpleasuresgenerallyrecognisedasgreatestarethoseattendingtheactivitiesoforganswhicharenormallyleftunexercisedforconsiderableintervals。Still，therearemanyfactsthatitdoesnotexplain——e。g。thegreatdifferencesinthepleasuresobtainableatanygiventimebydifferentstimulationsofthesamesense；thephenomenonexpressedintheproverbialphrase``L’appé；titvientenmangeant’’；
andthefactthattheexerciseofthevisualorgansafterapparentlydreamlesssleepdoesnotgiveappreciablykeenerpleasurethanitdoesatordinarytimes。Itwouldseemthatwemustseekforsomespecialcauseofthepleasurableeffectofintermittenceincertaincases。Andthiscannotbemerelythegreaterintensityofthenervousactionthattakesplacewhenlongunexercisedandwell-nourishednerve-centresarestimulated:forwhy，ifthatweretheexplanation，shouldthenormalconsciousnessoffullnervousactivity，graduallyattained——aswhenweareinfullswingofenergeticunweariedworkofaroutinekind——beoftennearlyorquiteindifferent？
Amongthevariouscompetinghypothesesofferedatthispointofourinquiry——nooneofwhich，Ibelieve，hasattainedanythinglikegeneralacceptanceascoveringthewholeground——Iselectfordiscussiononethathasspecialethicalinterest。