ARISI OTLE'S biology to this many-sid?d problem, proceeding very tentatively with a suspicion that after all we may be following not his mental processes, but our own. Undoubtedly a comprehensive examination of living organisms (animals rather than plants are in Aristotle's mind) must embrace the processes of formation of each animal, as well as of its characters when formed. He bids us remember that abstractions cannot form the subject of a natural science, and individual animals are the real existences, and not the genera formed by the mind. It is with indi- viduals that we have to deal, when trying to study their formation and characteristics and even when trying to form groups of genera and species. Thus he insists upon the concrete as the real object of study; yet he groups and classifies and seeks ever the general qualities in these concrete existences — even as he did in his famous theory of tragedy, in the Poetics, — and one should not draw back from the humblest details provided they lead us on and disclose the great design. Therefore: " Having already treated of the celestial world, as far as our conjectures could reach, we proceed to treat of animals, without omit-
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[47]
