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The suitable opening for this inquiry into the Vital Principle is to lay down the properties which appear, most especially, to belong to it. The animated being, then, seems to be especially distinguished from whatever is inanimate by the two properties of motion and feeling; and these two are almost the only distinctions which have been transmitted to us by the earlier writers upon the subject. Thus, some of them maintain that the Vital Principle is in the largest, fullest sense a motor power; and as they believed that nothing can impart motion unless it be self-motive, they assumed that the Vital Principle must be among beings which are self-moved. Hence Democritus says that it is a kind of fire and heat, and as forms and atoms are, according to him, infinite, he speaks of those which are spherical and apparent in the sun's beams, while passing through chinks in doors, as fire and Vital Principle; and further says, that those atoms, collectively, are the elements of universal nature. Leucippus, in like manner, is disposed to regard the spherical atoms as Vital Principle, both on account of those forms being best adapted for penetrating every where, and best able, from being self-motive, to give motion to other things; and thus they both assume that it is Vital Principle which imparts motion to living beings. Hence, too, they make breathing to be the boundary of life—for they maintain that the envelopment of animal bodies