But, while recognising all this, it is important that we should remember that facts alone are not sufficient to explain the origin of any doctrines, even those of social politics, and still less those of a purely scientific character. Ideas even are not independent of time and place. Similar conditions in the same epoch of history have not infrequently given rise to heterogeneous and even antagonistic theories—J. B. Say’s and Sismondi’s, for example, Bastiat’s and Proudhon’s, Schulze-Delitzsch’s and Marx’s, Francis Walker’s and those of Henry George. With what combination of historical circumstances are we to connect Cournot’s foundation of the Mathematical school in France, or how are we to account for the simultaneous discovery in three or four countries of the theory of final utility? Although anxious not to seem to make any extravagant claims for the superiority of the history of theory, we are not ashamed of repeating our regrets for the comparative neglect of economic history, and we are equally confident in claiming for our subject the right to be regarded as a distinct branch of the science.[1] We shall accordingly omit all reference to the history of economic facts and institutions except in so far as such reference seems indispensable to an understanding of either the appearance or disappearance of such and such a doctrine or to the better appreciation of the special prominence which a theory may have held at one moment, although it is quite unintelligible to us to-day. Sometimes even the facts are connected with the doctrines, not as causes, but as results, for, notwithstanding the scepticism of Cournot, who was wont to declare that the influence exerted by economists upon the course of events was about equal to the influence exerted by grammarians upon the development of language, it is impossible not to see a connection between the commercial treaties of 1860, say, and the teachings of the Manchester school, or between labour legislation and the doctrine of State Socialism. To write a history of economic doctrines which should not exceed the limits of a single volume was to attempt an almost impossible task, and the authors cannot pretend that they have accomplished such a difficult feat. Even a very summary exposition of such doctrines as could not possibly be neglected involved the omission of others of hardly less importance.