 His will was proved in 1627.Milles's economical works show the relation of the doctrines of the mercantilist writers to those of the later canonists.An advocate of the staple system on the ground that, while it made possible exchange without usury, it was favourable to freedom of enterprise and the development of commerce, he denounced the usurious practices of the new school, and argued that the monopoly of the Merchant Adventurers led to the growth of London at the expense of the outports, deprived merchants of free traffic, and diminished the revenue.