There is another method, which, starting out from principles, evident of themselves, develops science by way of conclusions drawn, after the manner of the geometricians. The apparent severity and simplicity of this method are very seductive, and very dangerous, when we have to deal not with figures, but with men; when the varied, complex and delicate exigencies which accumulate when human nature comes into play do not exactly square with the formula; and, when instead of dealing with abstractions, we have to tackle realities. One of our venerated teachers, the illustrious Rossi, thought he might remove the difficulty by drawing a distinction between _pure_ Political Economy and _applied_ Political Economy. It is not without a certain amount of hesitation that we dare differ with so high an authority; but confess we must, this distinction is far from satisfying us. The doubt it has left in our mind has been the principal cause which has inclined us to the historical method. “Rational Political Economy,” says Rossi, “is the science which investigates the nature, the causes and the movement of wealth, by basing itself on the general and constant facts of human nature, and of the external world. In applied Political Economy, the science is taken as the mean. Account is taken of external facts. Nationality, time and place play an important part.” Let us for a moment accept these definitions; what is the consequence? That there are two sciences, the one of which, purely speculative, has more to do with philosophy than with the permanent conflicts which agitate the world; the other of which could not alone furnish us with rules in practice, nor with a formulary for the measures to be taken in a given case, since such a pretension would be both vain and ridiculous, but which would inform the practical judgment of men charged with the solution of the numberless difficult and complicated questions which come up every day. If pure science refuses to interfere in the affairs of this world; if, as the learned originator of the doctrine we are just now considering gives us to understand, it would compromise the solution of questions by the intoxication of logic, and the ambition of perfect system; if, consequently, it is to be worshipped like a motionless and inactive divinity, how could this platonic satisfaction suffice us? Would not the opponents of economic doctrines be disposed to acknowledge all the principles, provided the consequences to be drawn from them were left to themselves; and would they not come to us, bristling with arguments drawn from the circumstances of nationality, time and space, to refute the possibility of applying pure science? On ne vaincra jamais les Romains que dans Rome.