" It assumed that values were a self-evident and universal truth, failing to see that the value character of the products of labour becomes firmly established only when they act as magnitudes of value. These magnitudes vary continually, independently of the will, foreknowledge and actions of the exchangers. Their own movement within society has for them the form of a movement made by things, and these things, far from being under their control, in fact control them. (167–8) "

― David Harvey , A Companion to Marx's Capital