Interestingly, right after the profound paragraph you quoted, he seems to reject what he has just said:
Such are the arguments (and others of the kind) which may cause difficulty on this point. Yet it is impossible that this should be the true view. For teeth and all other natural things either invariably or normally come about in a given way; but of not one of the results of chance or spontaneity is this true. We do not ascribe to chance or mere coincidence the frequency of rain in winter, but frequent rain in summer we do; nor heat in the dog-days, but only if we have it in winter. If then, it is agreed that things are either the result of coincidence or for an end, and these cannot be the result of coincidence or spontaneity, it follows that they must be for an end; and that such things are all due to nature even the champions of the theory which is before us would agree. Therefore action for an end is present in things which come to be and are by nature.Aristotle seems to have been beguiled by a teleological bias. He coulda been a contender. Moving along, however, he seems to recognize the existence of what we call mutations, but later on attributes them to a failed purpose:Further, where a series has a completion, all the preceding steps are for the sake of that. Now surely as in intelligent action, so in nature; and as in nature, so it is in each action, if nothing interferes. Now intelligent action is for the sake of an end; therefore the nature of things also is so. Thus if a house, e.g. had been a thing made by nature, it would have been made in the same way as it is now by art; and if things made by nature were made also by art, they would come to be in the same way as by nature. Each step then in the series is for the sake of the next; and generally art partly completes what nature cannot bring to a finish, and partly imitates her. If, therefore, artificial products are for the sake of an end, so clearly also are natural products. The relation of the later to the earlier terms of the series is the same in both. ...
Now mistakes come to pass even in the operations of art: the grammarian makes a mistake in writing and the doctor pours out the wrong dose. Hence clearly mistakes are possible in the operations of nature also. If then in art there are cases in which what is rightly produced serves a purpose, and if where mistakes occur there was a purpose in what was attempted, only it was not attained, so must it be also in natural products, and monstrosities will be failures in the purposive effort. Thus in the original combinations the ‘ox-progeny’ if they failed to reach a determinate end must have arisen through the corruption of some principle corresponding to what is now the seed.
He came THAT close...
I didn't read that far. Interesting. (Darwin does have this passage in one of his books, probably an introduction.)
I did find another translation where Aristotle did ascribe rain to Zeus. I don't know what the Greek version says (or if there are several.)
Aristotle is better at question than answers (a quality of being early.) He also thought the brain was designed to cool the blood but others though it was the seat of thought. In many cases, Aristotle was right.