, ▁which ▁forms ▁an ▁upper ▁limit ▁to ▁w ages , ▁and ▁the ▁rate ▁of ▁profit ▁as ▁the ▁ratio ▁between ▁the ▁sur plus ▁value ▁left ▁to ▁the ▁capital ist ▁after ▁pay ing ▁the ▁w age , ▁and ▁the ▁w age ▁itself , ▁thus ▁ex cluding ▁invest ments ▁in ▁capital ▁prior ▁to ▁production , ▁and ▁dis reg arding ▁pay ments ▁by ▁capital ists ▁in ▁rent ▁to ▁land l ords ▁and ▁interest ▁to ▁m one yl enders ▁which ▁must ▁come ▁from ▁sur plus ▁value ▁after ▁production . ▁▁ ▁This ▁ratio , ▁the ▁difference ▁between ▁the ▁value ▁created ▁by ▁the ▁" last ▁employed ▁worker " ▁and ▁the ▁w age ▁paid ▁to ▁that ▁worker , ▁which ▁constit utes ▁Marx ' s ▁use ▁of ▁the ▁word ▁" exp lo itation ." ▁ ▁Marx ▁con cludes ▁that ▁as ▁value ▁is ▁determined ▁by ▁labour , ▁and ▁as ▁profit ▁is ▁the ▁appropri ated ▁sur plus ▁value ▁remaining ▁after ▁pay ing ▁w ages , ▁that ▁the ▁maximum ▁profit ▁is ▁set ▁by ▁the ▁minimum ▁w age ▁necessary ▁to ▁sust ain ▁labour , ▁but ▁is ▁in ▁turn ▁adjust ed ▁by ▁the ▁overall ▁product ive ▁powers ▁of ▁labour ▁using ▁given ▁tools ▁and ▁machines , ▁the ▁length ▁of ▁the ▁work day , ▁the ▁intensity ▁of ▁work ▁demanded , ▁and ▁the ▁fl uct u ating ▁prices ▁of ▁comm od ities ▁such ▁as ▁met als ▁and ▁food st uff s ▁which ▁determine ▁how ▁much ▁a ▁worker ▁may ▁purchase ▁with ▁w ages ▁expressed ▁in ▁money . ▁All ▁of ▁these ▁factors ▁being ▁a ▁product ▁of ▁a ▁given ▁social ▁arrangement , ▁in