▁could ▁explain ▁how ▁that ▁value - price ▁relationship ▁operated , ▁without ▁contradict ing ▁themselves . ▁They ▁could ▁not ▁theoret ically ▁recon cile ▁the ▁reg ulation ▁of ▁comm od ity ▁trade ▁by ▁law ▁of ▁value , ▁with ▁profit - rece i pts ▁in ▁proportion ▁to ▁capital ▁employed ▁( r ather ▁than ▁in ▁proportion ▁to ▁labour - time ▁worked ). ▁Smith ▁and ▁Ric ardo ▁mo oted ▁the ▁concept ▁of ▁" natural ▁prices " ▁instead , ▁to ▁post ulate ▁a ▁" natural " ▁( in tr insic ) ▁self - bal ancing ▁t endency ▁of ▁mark ets — at ▁the ▁point ▁where ▁demand ▁and ▁supply ▁were ▁bal anced , ▁the ▁" natural " ▁price ▁( the ▁" true " ▁value ) ▁had ▁been ▁reached . ▁The ▁effect ▁was ▁that ▁their ▁" lab our ▁theory ▁of ▁value " ▁was ▁dis connected ▁from ▁their ▁theory ▁of ▁capital ▁distributions . ▁In ▁Marx ' s ▁theory , ▁a ▁true ▁supply / dem and ▁balance ▁in ▁the ▁capital ist ▁economy — which , ▁if ▁it ▁existed ▁at ▁all , ▁would ▁occur ▁only ▁incident ally — w ould ▁mean ▁that ▁goods ▁sold ▁at ▁their ▁normal ▁production ▁price , ▁but ▁this ▁did ▁not ▁automatically ▁or ▁necessarily ▁mean ▁that ▁they ▁sold ▁at ▁their ▁value . ▁The ▁production ▁prices ▁could ▁be ▁persist ently ▁above ▁or ▁below ▁product - values . ▁ ▁Econom ic ▁value ▁ ▁Econom ic ▁value ▁exists ▁necessarily , ▁according ▁to ▁Marx , ▁because ▁human ▁be ings ▁as ▁social ▁be ings ▁and ▁moral ▁subjects ▁must ▁co - oper atively ▁produce ▁and ▁econom ize