Like other sciences, Political Economy has remained destitute of a definition framed on strictly logical principles, or even of, what is more easily to be had, a definition exactly co-extensive with the thing defined. This has not, perhaps, caused the real bounds of the science to be, in this country at least, practically mistaken or overpassed; but it has occasioned--perhaps we should rather say it is connected with --indefinite, and often erroneous, conceptions of the mode in which the science should be studied. We proceed to verify these assertions by an examination of the most generally received definitions of the science. 1. First, as to the vulgar notion of the nature and object of Political Economy, we shall not be wide of the mark if we state it to be something to this effect:--That Political Economy is a science which teaches, or professes to teach, in what manner a nation may be made rich. This notion of what constitutes the science, is in some degree countenanced by the title and arrangement which Adam Smith gave to his invaluable work. A systematic treatise on Political Economy, he chose to call an _Inquiry into the Nature and Causes of the Wealth of Nations_; and the topics are introduced in an order suitable to that view of the purpose of his book. With respect to the definition in question, if definition it can be called which is not found in any set form of words, but left to be arrived at by a process of abstraction from a hundred current modes of speaking on the subject; it seems liable to the conclusive objection, that it confounds the essentially distinct, though closely connected, ideas of _science_ and _art_. These two ideas differ from one another as the understanding differs from the will, or as the indicative mood in grammar differs from the imperative. The one deals in facts, the other in precepts. Science is a collection of _truths_; art, a body of _rules_, or directions for conduct. The language of science is, This is, or, This is not; This does, or does not, happen. The language of art is, Do this; Avoid that. Science takes cognizance of a _phenomenon_, and endeavours to discover its _law_; art proposes to itself an _end_, and looks out for _means_ to effect it.