expositions of Political Economy itself; the strictness of purely scientific arrangement being thereby somewhat departed from, for the sake of practical utility. So far as it is known, or may be presumed, that the conduct of mankind in the pursuit of wealth is under the collateral influence of any other of the properties of our nature than the desire of obtaining the greatest quantity of wealth with the least labour and self-denial, the conclusions of Political Economy will so far fail of being applicable to the explanation or prediction of real events, until they are modified by a correct allowance for the degree of influence exercised by the other cause. Political Economy, then, may be defined as follows; and the definition seems to be complete:-- "The science which traces the laws of such of the phenomena of society as arise from the combined operations of mankind for the production of wealth, in so far as those phenomena are not modified by the pursuit of any other object." But while this is a correct definition of Political Economy as a portion of the field of science, the didactic writer on the subject will naturally combine in his exposition, with the truths of the pure science, as many of the practical modifications as will, in his estimation, be most conducive to the usefulness of his work. * * * * * The above attempt to frame a stricter definition of the science than what are commonly received as such, may be thought to be of little use; or, at best, to be chiefly useful in a general survey and classification of the sciences, rather than as conducing to the more successful pursuit of the particular science in question. We think otherwise, and for this reason; that, with the consideration of the definition of a science, is inseparably connected that of the _philosophic method_ of the science; the nature of the process by which its investigations are to be carried on, its truths to be arrived at. Now, in whatever science there are systematic differences of opinion --which is as much as to say, in all the moral or mental sciences, and in Political Economy among the rest; in whatever science there exist, among those who have attended to the subject, what are commonly called differences of principle, as distinguished from differences of matter-of-fact or detail,--the cause will be found to be, a difference in their conceptions of the philosophic method of the science. The parties who differ are guided, either knowingly or unconsciously, by different views concerning the nature of the evidence appropriate to the subject. They differ not solely in what they believe themselves to see, but in the quarter whence they obtained the light by which they think they see it.