It does not seem yet to be agreed what ought to be considered as the best definition of wealth, of capital, of productive labour, or of value;—what is meant by real wages;—what is meant by labour;—what is meant by profits;—in what sense the term ‘demand’ is to be understood,[1] _&c._ _&c._ As a remedy for such differences, it has been suggested, that a new and more perfect nomenclature should be introduced. But though the inconveniences of a new nomenclature are much more than counterbalanced by its obvious utility in such sciences as chemistry, botany, and some others, where a great variety of objects, not in general use, must be arranged and described so as best to enable us to remember their characteristic distinctions; yet in such sciences as morals, politics, and political economy, where the terms are comparatively few, and of constant application in the daily concerns of life, it is impossible to suppose that an entirely new nomenclature would be submitted to; and if it were, it would not render the same service to these sciences, in promoting their advancement, as the nomenclatures of Linnæus, Lavoisier, and Cuvier, to the sciences to which they were respectively applied. Under these circumstances, it may be desirable to consider what seem to be the most obvious and natural rules for our guidance in defining and applying the terms used in the science of political economy. The object to be kept in view should evidently be such a definition and application of these terms, as will enable us most clearly and conveniently to explain the nature and causes of the wealth of nations; and the rules chiefly to be attended to may, perhaps, be nearly included in the four following:— First. When we employ terms which are of daily occurrence in the common conversation of educated persons, we should define and apply them, so as to agree with the sense in which they are understood in this ordinary use of them. This is the best and more desirable authority for the meaning of words. Secondly. When the sanction of this authority is not attainable, on account of further distinctions being required, the next best authority is that of some of the most celebrated writers in the science, particularly if any one of them has, by common consent, been considered as the principal founder of it. In this case, whether the term be a new one, born with the science, or an old one used in a new sense, it will not be strange to the generality of readers, nor liable to be often misunderstood.