Before proceeding further, let us consider the nature of motion; for it may not only be untrue that Vital Principle is, as some affirm, essentially self-motive or capable of producing motion; but it may be one of those entities to which motion cannot possibly belong; and it has already been said that the motor is not necessarily itself in motion.
Everything moved admits of being moved in two ways: either by itself or by something else; and by something else we mean whatever is moved from being in something which is moving, as sailors for instance,—for they are not moved as is the vessel, since it is moved by itself, but they are moved from being in that which is moved. This is clear by reference to their limbs—a particular movement of the feet is walking, and walking is man's progression; but the sailors do not at that time move by walking. Since then motion may be spoken of in this two-fold sense, let us consider whether the Vital Principle moves by itself, and whether it partakes also of motion communicated to it. As there are four kinds of movement, translation, change, growth, decay, it follows that the Vital Principle should move according to one, or more than one, or all of them; and if it do not move by chance, then motion must be natural to it; and if so, then locality, for all the movements above alluded to are local.
But if Vital Principle be essentially self-motive, then accidental movement will not belong to it as to a white colour or a length of three cubits; for these properties do move, but then it is by accident, and owing to the bodies to which they belong happening to be in motion. Thus, there cannot be for them any locality as there will be for the Vital Principle, if it partakes of motion by its own nature. Although, however, it may be in motion by its own nature, it may still be moved by force, and if by force, still by nature; and the same holds good for the state of rest. Thus, the point towards which anything is by its nature moved, serves also by nature for its point of rest, as equally the point to which anything is moved by force serves also, by force, for its point of rest. It is not easy, however, even conjecturally to determine what will be the forced movements and forced states of rest of the Vital Principle—if its motion be upwards it will be fire, if downwards, earth, for such are the tendencies of those elements; and this conclusion applies equally to the intermediate movements. Since the Vital Principle besides appears to give motion to the body, it is probable that it communicates to the body the motions which it imparts to itself, and, if so, the converse may be true that it communicates to itself the motions which it imparts to the body. Now, the body is moved by translation, so that the Vital Principle should change with the body and be set free from it, either wholly or in its parts; and if this is admitted, it should follow that the Vital Principle, having gone forth from the body, might re-enter, and the consequence of this would be that the dead bodies of animals rise again. Could the Vital Principle be subject to casual motion communicated by some other power than its own, then an animal might be impelled to move by impulse from without; but it is noway necessary that that which is essentially self-motive should be moved by something else, unless by mere chance, any more than that which is good, in and for itself, should be so by or for the sake of something else. It may be confidently affirmed besides, that the Vital Principle, if it do move, is moved by objects which act upon the senses. Although, however, Vital Principle should be self-motive, it would still be in motion, and thus, as all motion is displacement of that which moved, as being moved, the Vital Principle might be displaced from its essence, unless its self-motion were a casual property; but self-motion is of its very essence.
Some philosophers maintain that the Vital Principle moves the body in which it is, as it is itself moving,—and this is the opinion of Democritus, who expresses himself almost in the words of the comic poet Philippus, who charges "Daedalus with having made a wooden Venus to become movable, when quicksilver was poured into it." Democritus, in fact, says much the same thing when he maintains that indivisible spheres are in motion, from their having been by nature constituted never to remain at rest, and that these spheres drag along with them and give motion to all things. But we will ask Democritus whether it is those self-same spheres which produce the state of rest, and it will be difficult or rather impossible for him to explain how they are to do so. It is not thus, besides, that the Vital Principle appears to give motion to an animal, as it acts, generally speaking, by some kind of election and thought.
It is in this same manner, however, that Timæus physiologically explains how the body is moved by the Vital Principle—that, from its being in motion, the body, with which it has been interwoven, is moved also; and having constituted it out of the elements, and divided it according to harmonic numbers, in order that it may have an innate sense of harmony, and that the universe may move in accordant orbits, he bent the straight line into a circle, and dividing that circle into two united in two parts, he again divided the single circle into seven others, as if to indicate that the orbits of the sky are the movements of the Vital Principle.
But, in the first place, it is not correct to say that the Vital Principle is magnitude, for Timæus evidently means that this Principle of the universe is such as is the so-called mind; and, then, that Principle of the universe can resemble neither the sentient nor the concupiscent faculty, as neither of these moves in a circle. The mind is one and continuous as is cogitation, and cogitation as are thoughts, and thoughts are, by concatenation, one, in the sense, not of magnitude, but of number; and, therefore, the mind is not continuous in the sense of magnitude, but either it is without parts, or, at all events, not continuous as magnitude. How, indeed, were it magnitude, is it to think—as a whole, or by some one of its parts? But parts must be regarded either as magnitude, or as points, if, indeed, a point may be regarded as a part; and, if parts be considered as points, then, as points are innumerable, the mind, clearly, will never be able to recount them all, and if, as magnitude, the mind will have to dwell very often, or rather continuously, upon the same subject. But it is manifest that thinking may be exercised once for all. If, besides, it suffice for thinking, that there should be contact by some one of its parts, why should it move in a circle, or why be magnitude? And if necessary for thinking that there should be contact by the whole circle, then what means contact by its parts? How, besides, shall that which has parts think by that which is without parts, or that which is without by that which has parts ? Thus, it follows that the mind must be that circle: for thinking is the movement of the mind, as the periphery is the movement of the circle ; and, if thinking be the periphery of the mind, the mind may be regarded as the circle, of which thinking is the periphery. But then the mind will be ever thinking, and necessarily so, since the peripheral movement is unceasing. Now, there are limits to practical thoughts, (as all such are for the sake of something else,) and so equally there are to speculative thoughts, in their reasons; and every reason is either a definition or a demonstration. Thus, demonstrations set out from a principle, and are, in some way, terminated by a syllogism or a conclusion; and even though not concluded, they do not revert to their principle, but, taking up another mean and extreme, they proceed onward; but the periphery, on the contrary, does revert to its point of departure. Definitions, however, are always limited. If, moreover, the same periphery recur often, the mind will be driven to think often upon the same subject, and thinking, besides, seems rather to be a kind of rest and a halt than motion; and this applies equally to the syllogism. As every condition, besides, which is compulsory and ungenial must be unhappy, so unless movement be an essential property of that mind, it must be moving against its nature, and it cannot but be painful for it to have been so connected with the body as to be unable to free itself from it; nay more, it is a lot to have been avoided, since it is better for the mind, as is commonly said, and to many seems reasonable, not to have been connected with a body at all. The cause too, of the circular movement of the sky is obscurely stated—for the essence of the Vital Principle is not the cause of that movement, as it never does, excepting it be by chance, so move, nor can the body be the cause, as it is the Vital Principle rather which gives motion to it; neither is it explained how it is better for the Vital Principle to be so circumstanced, and yet it ought to have been shewn that God had caused it to have a circular movement, as better for it to be in motion than at rest, and to move in that rather than in any other direction. But as this is an inquiry which belongs rather to other studies, it may, for the present, be laid aside.
The same incongruity which occurs in most of the theories upon Vital Principle is met with here, in that writers join Vital Principle to and place it in a body without having first settled for what purpose the body is to receive it, or how it is fitted for the office. It would seem, however, to be necessary that this should be settled, as it is through this connexion that the one acts and the other is acted upon, that the one moves and the other is moved; and these are relations which cannot be attributed to casual associations. There are writers who content themselves with saying what Vital Principle is, without determining any thing about the body its recipient, as if it were admissible, according to Pythagorean legends, that any kind of Vital Principle might clothe itself with any kind of body; but every thing, on the contrary, seems to have its own particular character and form. Such opinions are, in fact, very much like maintaining that the builder's art may be undertaken with musical instruments; but we affirm that as each art must employ its own instruments, so each Vital Principle must employ its own body.