The answers to these questions form a considerable part of Aristotle’s philosophy where we are unable to follow him. For the limited field of biology, however, the question is on somewhat narrower lines. ‘What,’ he asks, ‘are the forces by which the hand or the body was fashioned into shape? The wood carver will perhaps say, by the axe or the auger.... But it is not enough for him to say that by the stroke of his tool this part was formed into a concavity, that into a flat surface; but he must state the reasons why he struck his blow in such a way as to effect this and what his final object was ... [similarly] the true method [of biological science] is to state what the definite characters are that distinguish the animal as a whole; to explain what it is both in substance and in form, and to deal after the same fashion with its several organs.... If now this something, that constitutes the form of the living being, be the soul, or part of the soul, or something that, without the soul, cannot exist, (as would seem to be the case, seeing at any rate that when the soul departs, what is left is no longer a living animal, and that none of the parts remain what they were before, excepting in mere configuration, like the animals that in the fable are turned into stone;) ... then it will come within the province of the natural philosopher to inform himself concerning the soul, and to treat of it, either in its entirety, or, at any rate, of that part of it which constitutes the essential character of an animal; and it will be his duty to say what this soul or this part of a soul is.’[25] Thus in the Aristotelian writings the discussion of the nature and orders of ‘soul’ is almost inseparable from the subjects now included under the term Biology. [25] _De partibus animalium_, i. 1; 641ᵅ 7. There can be no doubt that through much of the Aristotelian writings runs a belief in a _kinetic_ as distinct from a static view of existence. It cannot be claimed that he regarded the different kinds of living things as actually passing one into another, but there can be no doubt that he fully realized that the different kinds can be arranged in a series in which the gradations are easy. His scheme would be something like that represented on p. 30 (Fig. 7 a).