Market economy implies a self-regulating system of markets; in slightly more technical terms, it is an economy directed by market prices and nothing … - Karl Polanyi

Equivalencies between the units of different goods were meant to express proportions that both resulted from the conditions existing in that society and contributed to the maintenance of those conditions. The "justice" expressed in the equivalency is a reflection of the "justness" of the society it mirrors. How could this be otherwise, once the status rewards and standards of life that obtain in the society were necessarily reflected in the equivalencies? Consequently, what we are wont to call gain, profit, wages, rent, or other revenue, must be comprised in the equivalency, if those revenues are required to maintain existing social relations and values. This was the rationale of the "just price" as postulated by the schoolmen. Far from being the expression of a pious hope or of an uplifted thought irrelevant to "economic realities," as the orthodox economic classics tended to believe, the just price was an equivalency, the actual amount of which was determined either by municipal authority or by the actions of the guildsmen in the market, but in either case according to determinants relevant to the concrete social situation. The guildsmen who refused to sell below a price that would endanger the standard of his colleagues, and equally refused to accept a price that would secure for him a revenue higher than that approved by his colleagues, cooperated to create the "just price" as effectively as the municipal authority that could be called upon to fix the price directly in order to uphold these very principles.

The road to the free market was opened and kept open by an enormous increase in continuous, centrally organized and controlled interventionism. To make Adam Smith's "simple and natural liberty" compatible with the needs of a human society was a most complicated affair.

Robert Owen’s was a true insight: market economy if left to evolve according to its own laws would create great and permanent evils.