Precisely because so many advocates of a theistic view of the world have thought that for the sake of the theistic idea of creation they were obliged to suppose a primitive origin of all the organic species, and because, nevertheless, the fact is patent that in the course of the pre-historic thousands of years myriads of species came and perished, not to return again, they became liable to the reproach on the part of the adversaries of theism, that the Creator, as they supposed him, makes unsuccessful attempts, which he has to throw away, as the potter a defective vessel, until he finally succeeds in making something durable and useful; and this objection was and is still made, not only to these superficial theists and their unhappily-selected and indefensible position, but to {261} the whole view of the world of theism itself and to the faith in God and the Creator in general. For all these reasons, we can from the religious point of view but welcome the idea of a descent of species. Philologists have, if we are correctly informed, the canon that as a rule the more difficult text is the more correct one; but we doubt whether those should adopt this canon who try to read in the book of nature, whether with the eye of science or with that of religion--unless the faculty of reasoning is given to us in order to conceal the truth. But, we have also to look for a manner of reconciling theism with all the different possibilities under which a descent is at all reasonable and conceivable. One of these possibilities is that of an entirely successive development of species out of one another by imperceptibly small transitions; and of this we shall soon speak. Another is the possibility of a descent by leaps, through a metamorphosis of germs or a heterogenetic generation. The real causes of such a heterogenetic generation, if it took place at all, have not yet been found; therefore we have to treat only of the abstract possibilities of its conceivableness. There are two such possibilities.