, ▁attitude ▁toward ▁the ▁idea ▁of ▁‘ me as uring ’ ▁variations ▁in ▁the ▁purch asing ▁power ▁of ▁money ▁( reci pro cal ▁of ▁price ▁level ) ▁by ▁index ▁numbers . ▁They ▁were ▁incl ined ▁to ▁refuse ▁citizens hip ▁to ▁the ▁concept ▁of ▁price ▁level ▁and , ▁in ▁any ▁case , ▁to ▁den y ▁its ▁meas ur ability ▁on ▁principle ▁[ he ▁supplies ▁a ▁reference ▁to ▁von ▁M ises ]. ▁In ▁view ▁of ▁the ▁fact ▁that ▁so ▁many ▁econom ists ▁placed ▁and ▁place ▁an ▁un crit ical ▁trust ▁in ▁index ▁figures ▁without ▁trou bling ▁themselves ▁about ▁their ▁meaning ▁[ he ▁supplies ▁a ▁foot note ▁referring ▁to ▁Ke yn es ], ▁this ▁attitude ▁provided ▁a ▁much ▁needed ▁ant id ote . ▁and ▁the ▁foot note ▁reads : ▁In ▁the ▁last ▁ten ▁years ▁or ▁so ▁a ▁reaction ▁has ▁set ▁in ▁of ▁which ▁the ▁most ▁important ▁sympt om ▁is ▁that ▁Lord ▁Ke yn es , ▁who ▁in ▁the ▁Tre at ise ▁on ▁M oney   ▁( 1 9 3 0 ) ▁evidently ▁attached ▁much ▁importance ▁to ▁price ▁indices ▁as ▁tools ▁of ▁theoretical ▁analysis , ▁entirely ▁avoided ▁their ▁use ▁in ▁his ▁General ▁Theory   ▁( 1 9 3 6 ). ▁Ke yn es ▁viewed ▁real ▁values ▁as ▁introdu cing ▁unnecessary ▁im prec ision ▁rather ▁than ▁as ▁being ▁meaning less . ▁He ▁comments ▁that ... ▁... the ▁well - known , ▁but ▁un av oid able , ▁element ▁of ▁v ag uen ess ▁which ▁admitted ly ▁att ends ▁the ▁concept ▁of ▁the ▁general ▁price - level ▁makes ▁this