While thus, on the one hand, the Greek religion by its inner evolution, was tending to destroy itself, on the other hand it was threatened from without by the attack of what we should call the "scientific spirit." A system so frankly anthropomorphic was bound to be weak on the speculative side. Its appeal, as we have seen, was rather to the imagination than to the intellect, by the presentation of a series of beautiful images, whose contemplation might offer to the mind if not satisfaction, at least acquiescence and repose. A Greek who was not too inquisitive was thus enabled to move through the calendar of splendid festivals and fasts, charmed by the beauty of the ritual, inspired by the chorus and the dance, and drawing from the familiar legends the moral and aesthetic significance with which he had been accustomed from his boyhood to connect them, but without ever raising the question, Is all this true? Does it really account for the existence and nature of the world? Once, however, the spell was broken, once the intellect was aroused, the inadequacy of the popular faith, on the speculative side, became apparent; and the mind turned aside altogether from religion to work out its problems on its own lines. We find accordingly, from early times, physical philosophers in Greece free from all theological preconceptions, raising from the very beginning the question of the origin of the world, and offering solutions, various indeed but all alike in this, that they frankly accept a materialistic basis. One derives all things from water, another from air, another from fire; one insists upon unity, another on a plurality of elements; but all alike reject the supernatural, and proceed on the lines of physical causation. The opposition, to use the modern phrase, between science and religion, was thus developed early in ancient Greece; and by the fifth century it is clear that it had become acute. The philosopher Anaxagoras was driven from Athens as an atheist; the same charge, absurdly enough, was one of the counts in the indictment of Socrates; and the physical speculations of the time are a favourite butt of that champion of orthodoxy, Aristophanes. To follow up these speculations in detail would be to wander too far from our present purpose; but it may be worth while to quote a passage from the great comedian, to illustrate not indeed the value of the theories ridiculed, but their generally materialistic character, and their antagonism to the popular faith. The passage selected is part of a dialogue between Socrates and Strepsiades, one of his pupils; and it is introduced by an address from the chorus of "Clouds", the new divinities of the physicist: CHORUS OF CLOUDS.