This paper analyses the influence of James Steuart on Karl Marx’s monetary thought. It deals more specifically with Marx’s rejection of an automatic mechanism that links variations in the quantity of money to their direct impact on prices. Steuart’s pioneering discoveries in economics inaugurate an anti-quantity theory tradition that Marx supported and which fed his own conception of money and credit. Here, we deal with the criticism of the assumptions of the quantity theory of money (QTM), the specifically social character of labour which creates exchange value, the distinction between the functions of money, the difference between income spending and capital advances, and the difference between simple circulation and reflux of money credit.