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。