InterestandProfitofEnterpriseInterest，aswehaveseeninthetwoprecedingchapters，appearsoriginally，isoriginally，andremainsinfactmerelyaportionoftheprofit，i。e。，ofthesurplus-value，whichthefunctioningcapitalist，industrialistormerchanthastopaytotheownerandlenderofmoney-capitalwheneverheusesloanedcapitalinsteadofhisown。Ifheemploysonlyhisowncapital，nosuchdivisionofprofittakesplace；thelatteristhenentirelyhis。
Indeed，aslongastheownersofthecapitalemployitontheirowninthereproductionprocess，theydonotcompeteindeterminingtherateofinterest。Thisaloneshowsthatthecategoryofinterest——impossiblewithoutdeterminingtherateofinterest——isalientothemovementsofindustrialcapitalassuch。”Therateofinterestmaybedefinedtobethatproportionalsumwhichthelenderiscontenttoreceive，andtheborrowertopay，annually，orforanylongerorshorterperiod，fortheuseofacertainamountofmoneyedcapital……Whentheownerofacapitalemploysitactivelyinreproduction，hedoesnotcomeundertheheadofthosecapitalists，theproportionofwhom，tothenumberofborrowers，determinestherateofinterest。”Th。
Tooke，HistoryofPrices，London，1838，II，pp。355-56。Itisindeedonlytheseparationofcapitalistsintomoney-capitalistsandindustrialcapitaliststhattransformsaportionoftheprofitintointerest，thatgenerallycreatesthecategoryofinterest；anditisonlythecompetitionbetweenthesetwokindsofcapitalistswhichcreatestherateofinterest。
Aslongascapitalfunctionsintheprocessofreproduction-assumingthatitevenbelongstotheindustrialcapitalistandhehasnoneedofpayingitbacktoalender——thecapitalist，asaprivateindividual，doesnothaveathisdisposalthiscapitalitself，butonlytheprofit，whichhemayspendasrevenue。Aslongashiscapitalfunctionsascapital，itbelongstotheprocessofreproduction，istiedupinit。Heis，indeed，itsowner，butthisownershipdoesnotenablehimtodisposeofitinanyotherway，solongasheusesitascapitalfortheexploitationoflabour。
Thesameistrueofthemoney-capitalist。Solongashiscapitalisloanedoutandtherebyservesasmoney-capital，itbringshiminterest，aportionoftheprofit，buthecannotdisposeoftheprincipal。Thisisevidentwheneverheloansouthiscapitalfor，say，ayear，ormore，andreceivesinterestatcertainstipulatedtimeswithoutthereturnofhisprincipal。