Withthisdoctrine，thatofcostofproductionasdeterminingpricecollapses，andtheprincipleemergesthatitisnotcostof
production，butdemandandsupply，onwhichdomestic，nolessthaninternational，valuesdepend，thoughthisformulawill
requiremuchinterpretationbeforeitcanbeusedsafelyandwithadvantage。ThusLeslieextendstothewholeofthenational
industrythepartialnegationoftheolderdogmaintroducedbyCairnesthroughtheideaofnon—competinggroups。Hedoes
not，ofcourse，disputetherealoperationofcostofproductiononpriceinthelimitedareawithinwhichratesofprofitand