But while Poetry depends upon Philosophy for the principles on which its types are constructed, it influences Polity by the direction which it gives to those types. In every operation that man undertakes, he must imagine before he executes, as he must observe before he imagines. He can never produce a result which he has not conceived first in his own mind. In the simplest application of mechanics or geometry he finds it necessary to form a mental type, which is always more perfect than the reality which it precedes and prepares. Now none but those who confound poetry with verse-making can fail to see that this conception of a type is the same thing as esthetic imagination, under its simplest and most general aspect. Its application to social phenomena, which constitute the chief sphere both of Art and of Science, is very imperfectly understood as yet, and can hardly be said to have begun, owing to the want of any true theory of society. The real object of so applying it is, that it should regulate the formation of social Utopias; subordinating them to the laws of social development as revealed by history. Utopias are to the Art of social life what geometrical and mechanical types are to their respective arts. In these their necessity is universally recognized; and surely the necessity cannot be less in problems of such far greater intricacy. Accordingly we see that, notwithstanding the empirical condition in which political art has hitherto existed, every great change has been ushered in, one or two centuries beforehand, by an Utopia bearing some analogy to it. It was the product of the esthetic genius of Humanity working under an imperfect sense of its conditions and requirements. Positivism, far from laying an interdict on Utopias, tends rather to facilitate their employment and their influence, as a normal element in society. Only, as in the case of all other products of imagination, they must always remain subordinated to the actual laws of social existence. And thus by giving a systematic sanction to this the Poetry, as it may be called, of Politics, most of the dangers which now surround it will disappear. Its present extravagances arise simply from the absence of some philosophical principle to control it, and therefore there is no reason for regarding them with great severity.