Meanwhile I thought I had discovered not only that faith, during the eleventh, twelfth, and early thirteenth centuries, spoke by preference through architecture, but also that in France and Syria, at least, a precise relation existed between the ecclesiastical and military systems of building, and that the one could not be understood without the other. In the commercial cities of the same epoch, on the contrary, the religious idea assumed no definite form of artistic expression, for the Gothic never flourished in Venice, Genoa, Pisa, or Florence, nor did any pure school of architecture thrive in the mercantile atmosphere. Furthermore, commerce from the outset seemed antagonistic to the imagination, for a universal decay of architecture set in throughout Europe after the great commercial expansion of the thirteenth century; and the inference I drew from these facts was, that the economic instinct must have chosen some other medium by which to express itself. My observations led me to suppose that the coinage might be such a medium, and I ultimately concluded that, if the development of a mercantile community is to be understood, it must be approached through its money. Another conviction forced upon my mind, by the examination of long periods of history, was the exceedingly small part played by conscious thought in moulding the fate of men. At the moment of action the human being almost invariably obeys an instinct, like an animal; only after action has ceased does he reflect. These controlling instincts are involuntary, and divide men into species distinct enough to cause opposite effects under identical conditions. For instance, impelled by fear, one type will rush upon an enemy, and another will run away; while the love of women or of money has stamped certain races as sharply as ferocity or cunning has stamped the lion or the fox. Like other personal characteristics, the peculiarities of the mind are apparently strongly hereditary, and, if these instincts be transmitted from generation to generation, it is plain that, as the external world changes, those who receive this heritage must rise or fall in the social scale, according as their nervous system is well or ill adapted to the conditions to which they are born. Nothing is commoner, for example, than to find families who have been famous in one century sinking into obscurity in the next, not because the children have degenerated, but because a certain field of activity which afforded the ancestor full scope, has been closed against his offspring. Particularly has this been true in revolutionary epochs such as the Reformation; and families so situated have very generally become extinct.