Manufactures, according to Quesnay, do no more than pay the wages and expenses of the workmen engaged in them. But agriculture not only pays wages and expenses, but produces a surplus, which is the revenue of the land. He divides the nation into three classes: (1) the productive, which cultivates the soil; (2) the proprietary, which includes the sovereign, the land-owners, and those who live by tithes, in other words the nobility and the clergy; and (3) the sterile, which embraces all men who labor otherwise than in agriculture, and whose expenses are paid by the productive and proprietary classes. Therefore he argues that taxes should be based directly on the net product of real estate, and not on wages nor on chattels. In other words, all taxes should be levied directly on the income derived from land, and indirect taxation in every shape should be abolished. Liberty of agriculture, liberty of commerce! "Let every man be free to cultivate in his field such crops as his interest, his means, the nature of the ground may suggest as rendering the greatest possible return." "Let complete liberty of commerce be maintained; for the regulation of commerce, both internal and external, which is most safe, most accurate, most profitable to the nation, consists in full liberty of competition." These doctrines of Quesnay, joined with the ideas of property and security, form the basis of the modern school of individualism. [Footnote: Lavergne, _Les Économistes,_ 105. Quesnay, _Oeuvres,_ 233, 306, 331 _(Maximes du gouvernement économique d'un royaume agricole Maxime,_ iii. v. xiii. xxv.). Turgot, iv. 305. Bois-Guillebert appears to have been the principal precursor of the Physiocrats. Horn, _L'Économie politique avant les Physiocrates, passim;[Greek physis] = nature,[Greek kratos] = power.]