Whatever the philosophical or methodological approach economists have taken to their discipline, whatever view they have taken of its scope, objectives and analytical techniques, the theory of value – with its associated theory of distribution – has been a key feature of the disciplinary matrix or paradigm to which they have chosen to conform. The prevailing concept of value and the use made of it has altered, chameleon-fashion, to match the currently accepted economic doctrines. In pre-mercantilist periods, when it would be an exaggeration to say that there was an explicit theory of value, the concept of value reflected current attitudes to economic questions. For example, in medieval scholastic doctrine the value of the commodity tended to be identified with the morally right price. In a static, parochialised economic and social order the just price would equal the customary price, reflecting a socially accepted scale of values, and the whole community would know what the fair price ought to be. However when the market became more dominant in economic life, there was an increasing tendency for the concept of the just price to coincide with the normal (competitive) market price, including an element of normal profit. For this too became a customary price which could be justified as being the proper one. Realists such as Thomas Aquinas did not hesitate to identify the actual market price, even when inflated by temporary scarcity, with the just price.