It is the almost unlimited extent of the wants of man in the social state, and the consequent multiplicity and complexity of his means--both his wants and means proceeding from the range of his mental faculties--which have rendered it so difficult to observe and explain the laws which govern the production, distribution, and consumption of those articles of utility, essential to the subsistence and comfort of the human race, which we call Wealth. It is not more than a century ago that even those who had "a great deal of philosophy" first began to apply themselves to observe "what is seen every day" exercising, in the course of human industry, the greatest influence on the condition and character of individuals and nations. The properties of light were ascertained by Sir Isaac Newton long before men were agreed upon the circumstances which determined the production of a loaf of bread; and the return of a comet after an interval of seventy-six years was pretty accurately foretold by Dr. Halley, when legislators were in almost complete ignorance of the principle which regularly brought as many cabbages to Covent Garden as there were purchasers to demand them. Since those days immense efforts have been made to determine the great circumstances of our social condition, which have such unbounded influence on the welfare of mankind. But, unhappily for themselves and for others, many of every nation still remain in comparative darkness, with regard even to the elementary truths which the labours of some of the most acute and benevolent inquirers that the world has produced have succeeded in establishing. Something of this defect may be attributed to the fact that subjects of this nature are considered difficult of comprehension. Even the best educated sometimes shrink from the examination of questions of political economy when presented in their scientific form. Charles Fox said that he could not understand Adam Smith. And yet Adam Smith's 'Wealth of Nations' is essentially an amusing book in many parts. Matters affecting the interests of every human being, and involving a variety of facts having relation to the condition of mankind in every age and country, are not necessarily, as has been supposed, dry and difficult to understand, and consequently only to be approached by systematic students. In this belief it is proposed in this volume to exhibit the natural operation of the principles by which Industry, as well as every other exchangeable property, must be governed. The writer has to apply all the universal laws which regulate the exchanges of mankind to the direction of that exchange which the great bulk of the people are most interested in carrying forward rapidly, certainly, and uninterruptedly--the exchange of Labour for Capital. But he has also to regard those laws with especial reference to that mighty Power which has become so absorbing and controlling in our own day--the Power of Science applied to the Arts, or, in other words, Knowledge.