"Although we cannot demonstrate that the production of a species by modification is a thing impossible to nature, the number of contrary probabilities is so enormous that, even philosophically, we can scarcely doubt it; for if any species has been produced by the modification of another, if the species of ass has been derived from that of the horse, this could have been done only successively and by gradual steps: there would have been between the horse and ass a great number of intermediate animals, the first of which would gradually differ from the nature of the horse, and the last would gradually approach that of the ass; and why do we not see to-day the representatives, the descendants of those intermediate species? Why are only the two extremes living?" (tome iv., p. 390). "If we once admit that the ass belongs to the horse family, and that it only differs from it because it has been modified (_dégénéré_), we may likewise say that the monkey is of the same family as man, that it is a modified man, that man and the monkey have had a common origin like the horse and ass, that each family has had but a single source, and even that all the animals have come from a single animal, which in the succession of ages has produced, while perfecting and modifying itself, all the races of other animals" (tome iv., p. 382). "If it were known that in the animals there had been, I do not say several species, but a single one which had been produced by modification from another species; if it were true that the ass is only a modified horse, there would be no limit to the power of nature, and we would not be wrong in supposing that from a single being she has known how to derive, with time, all the other organized beings" (_ibid._, p. 382). The next sentence, however, translated, reads as follows: "But no. It is certain from revelation that all animals have alike been favored with the grace of an act of direct creation, and that the first pair of every species issued fully formed from the hands of the Creator" (tome iv., p. 383). In which of these views did Buffon really believe? Yet they appear in the same volume, and not at different periods of his life. He actually does say in the same volume (iv., p. 358): "It is not impossible that all species may be derivations (_issues_)." In the same volume also (p. 215) he remarks: "There is in nature a general prototype in each species on which each individual is modelled, but which seems, in being realized, to change or become perfected by circumstances; so that, relatively to certain qualities, there is a singular (_bizarre_) variation in appearance in the succession of individuals, and at the same time a constancy in the entire species which appears to be admirable."