The fall of civilizations is the most striking, and, at the same time, the most obscure, of all the phenomena of history. It is a calamity that strikes fear into the soul, and yet has always something so mysterious and so vast in reserve, that the thinker is never weary of looking at it, of studying it, of groping for its secrets. No doubt the birth and growth of peoples offer a very remarkable subject for the observer; the successive development of societies, their gains, their conquests, their triumphs, have something that vividly takes the imagination and holds it captive. But all these events, however great one may think them, seem to be easy of explanation; one accepts them as the mere outcome of the intellectual gifts of man. Once we recognize these gifts, we are not astonished at their results; they explain, by the bare fact of their existence, the great stream of being whose source they are. So, on this score, there need be no difficulty or hesitation. But when we see that after a time of strength and glory all human societies come to their decline and fall—all, I say, not this or that; when we see in what awful silence the earth shows us, scattered on its surface, the wrecks of the civilizations that have preceded our own—not merely the famous civilizations, but also many others, of which we know nothing but the names, and some, that lie as skeletons of stone in deep world-old forests, and have not left us even this shadow of a memory; when the mind returns to our modern States, reflects on their extreme youth, and confesses that they are a growth of yesterday, and that some of them are already toppling to their fall: then at last we recognize, not without a certain philosophic shudder, that the words of the prophets on the instability of mortal things apply with the same rigour to civilizations as to peoples, to peoples as to States, to States as to individuals; and we are forced to affirm that every assemblage of men, however ingenious the network of social relations that protects it, acquires on the very day of its birth, hidden among the elements of its life, the seed of an inevitable death. But what is this seed, this principle of death? Is it uniform, as its results are, and do all civilizations perish from the same cause?