Comentario Resolutorio de Cambios (Commentary on Exchange)
1556
Summary
Martín de Azpilcueta's 1556 treatise on monetary exchange, containing the earliest clear statement of what would become the quantity theory of money. Azpilcueta observed that in countries where money is plentiful, prices are high, while where money is scarce, prices are low — deducing that the value of money itself varies with its supply. This anticipates by more than a century the full development of quantity theory and marks Azpilcueta as a genuine founder of monetary economics.