the principles laid down in them are often stated only in a cursory and incidental manner. Their authors frequently appear not to be aware of the importance of the truths which they have discovered; and in none of them is
anything like a connected view of political economy to be found.
The only work that was given to the world before the "Wealth of Nations," in which an attempt was made to expound the principles of political economy in a logical and systematic manner, was the Economical Table of the celebrated Quesnay, a French physician, which was published in 1758: but the theory of this distinguished economist is very erroneous. Having been educated in the country, he was naturally inclined to regard agriculture with partiality; and he had come to the conclusion, that it was the only species of industry which could possibly contribute to increase the wealth of a nation. Everything which ministers to the wants of man, must be originally derived from the earth; and the earth, therefore, Quesnay contended, must be the only source of wealth. As manufacturers and merchants do not realize any surplus in the shape of rent, he conceived that their operations, though highly useful, could not add any greater value to commodities than the value of the capital consumed by them. Into this erroneous theory he seems to have been led, from being unable to explain the nature of rent; and from being unacquainted with that fundamental principle in political economy, that labour is the cause of exchangeable value.
But, though Quesnay conceived agriculture to be the only source of wealth, the principles of his system fortunately did not lead him to solicit for it any exclusive protection. On the contrary, he contended that the interest of all the different classes of society would be best promoted, by the establishment of a system of perfect freedom. It must, he conceived, be advantageous to the cultivators of the soil, that the industry of manufacturers and merchants should not be fettered; for the more liberty they enjoyed, the greater would be their competition, and in consequence the cheaper would their services be rendered to the agriculturists. On the other hand, it was the interest of the manufacturers, that the cultivators of the soil should also have perfect freedom; for the greater liberty they enjoyed, the more would their industry increase that surplus fund, from which, according to his theory, the whole national revenue was ultimately derived.
It was in the work of Dr Smith, that the sources of the wealth and prosperity of nations, were first fully and correctly explored, and, in a systematic manner, distinctly explained; and that the advantages to be derived from commercial freedom, were first satisfactorily established. In opposition to the principles of the commercial system, Dr Smith showed that wealth does not consist in gold and silver, but in the abundance of the various necessaries, conveniences, and luxuries of life; that labour is the only source of wealth; and, in opposition to the French economists, that labour is productive, when employed in manufactures and commerce, as well as in agriculture. He has investigated the various causes by which labour may be rendered most productive; and has shown how immensely its powers are increased, by being divided among different individuals, or nations. He has proved, with great power of reasoning, that all restrictions upon either the internal or external commerce of a country, are in the highest degree absurd and pernicious; and that the progress of real opulence will be most rapidly accelerated, when the industry of every individual and nation is employed in the production of those articles for which, either from natural or artificial causes, they are best adapted, and when the most unlimited freedom of making exchanges is everywhere allowed. "It is the maxim of every prudent master of a family," he remarks, B. iv. c. 2, "never to attempt to make at home, what it will cost him more to make than to buy. The tailor
