self-fulfilment it keeps itself pure or, on the contrary, becomes dull and unclear or evasively splits into numerous varieties--and finally a _life-duration of this form_, which (unless, again, incident intervenes to shorten it) leads naturally to a senility of the species and finally to its disappearance. As for mankind, discoveries of the Diluvial age indicate more and more pointedly that the man-forms existing then correspond to those living now; there is not the slightest trace of evolution towards a race of greater utilitarian “fitness.” And the continued failure to find man in the Tertiary discoveries indicates more and more clearly that the human life-form, like every other, originates in a sudden mutation (_Wandlung_) of which the “whence,” “how,” and “why” remain an impenetrable secret. If, indeed, there were evolution in the English sense of the word, there could be neither defined earth-strata nor specific animal-classes, but only a single geological mass and a chaos of living singular forms which we may suppose to have been left over from the struggle for existence. But all that we see about us impels us to the conviction that again and again profound and very sudden changes take place in the being of plants and animals, changes which are of a cosmic kind and nowise restricted to the earth’s surface, which are beyond the ken of human sense and understanding in respect of causes, if not indeed in all respects.[35] So, too, we observe that swift and deep changes assert themselves in the history of the great Cultures, without assignable causes, influences, or purposes of any kind. The Gothic and the Pyramid styles come into full being as suddenly as do the Chinese imperialism of Shi-hwang-ti and the Roman of Augustus, as Hellenism and Buddhism and Islam. It is exactly the same with the events in the individual life of every person who counts at all, and he who is ignorant of this knows nothing of men and still less of children. Every being, active or contemplative, strides on to its fulfilment by _epochs_ and we have to assume just such epochs in the history of solar systems and the world of the fixed stars. The origins of the earth, of life, of the free-moving animal _are_ such epochs, and, therefore, mysteries that we can do no more than accept.[36] IV