The same arguments which induce us to believe that there is a soul in man apply to animals. The world has generally believed that in man, beside the body, there is also soul. Why have people believed it? The reason probably is, that, beside all that can be accounted for as the result of the juxtaposition of material particles, there remains a very important element unaccounted for. Mechanical and physical agency may explain much, but the most essential characteristic of vital phenomena they do not explain. They do not account for the unity in variety, permanence in change, growth from within by continuous processes, coming from the vital functions in an organized body. Every such body has a unity peculiar to itself, which cannot be considered the result of the collocation of material molecules. It is a unity which controls these molecules, arranges and rearranges them, maintains a steady activity, carries the body through the phenomena of growth, and causes the various organs to coöperate for the purposes of the whole. The vital power is not merely the result of material phenomena, but it reacts on these as a cause. Add to this that strange phenomenon of human consciousness, the sense of personality,—which is the clear perception of selfhood as a distinct unchanging unit, residing in a body all of whose parts are in perpetual flux,—and we see why the opinion of a soul has arisen. It has been assumed by the common sense of mankind that in every living body the cause of the mode of existence of each part is contained in the whole. As soon as death intervenes each part is left free to pass through changes peculiar to itself alone. Life is a power which acts from the whole upon the parts, causing them to resist chemical laws, which begin to act as soon as life departs. The unity of a living body does not result from an ingenious juxtaposition of parts, like that of a watch, for example. For the unity of a living body implies that which is called "the vital vortex," or perpetual exchange of particles.
A watch or clock is the nearest approach which has been made by man to the creation of a living being. A watch, for instance, contains the principle of its action in itself, and is not moved from without; in that it resembles a living creature. We can easily conceive of a watch which might be made to go seventy years, without being wound up. It might need to be oiled occasionally, but not as often as an animal needs to be fed. A watch is also like a living creature in having a unity as a whole not belonging to the separate parts, and to which all parts conspire,—namely, that of marking the progress of time. Why, then, say that a man has a soul, and that a watch has not? The difference is this. The higher principle of unity in the watch, that is, its power of marking time, is wholly an effect, and never a cause. It is purely and only the result of the arrangement of wheels and springs; in other words, of material conditions. But in man, the principle of unity is also a cause. Life reacts upon body. The laws of matter are modified by the power of life, chemical action is suspended, living muscles are able to endure without laceration the application of forces which would destroy the dead fibre. So the thought, the love, the will of a living creature react on the physical frame. A sight, a sound, a few spoken words, a message seen in a letter, cause an immense revulsion in the physical condition. Something is suddenly told us, and we faint away, or even die, from the effect of the message. Here mind acts upon matter, showing that in man mind is not merely a result, but also a cause. Hence men have generally believed in the existence of a soul in man. They have not been taught it by metaphysicians, it is one of the spontaneous inductions of common sense from universal experience.
But this argument applies equally to prove a soul in animals. The same reaction of soul on body is constantly apparent. Every time that you whistle to your dog, and he comes bounding toward you, his mind has acted on his body. His will has obeyed his thought, his muscles have obeyed his will. The cause of his motion was mental, not physical. This is too evident to require any further illustration. Therefore, regarding the soul as a principle of life, connected with the body but not its result, or, in other words, as an immaterial principle of activity, there is the same reason for believing in the soul of animals that there is for believing in the soul of man.
But when we ask as to the nature of the animal soul, and how far it is analogous to that of man, we meet with certain difficulties. Let us see then how many of the human qualities of the soul are to be found in animals, and so discover if there is any remainder not possessed by them, peculiar to ourselves.
That the vital soul, or principle of life, belongs equally to plants, animals, and men, is evident. This is so apparent as to be granted even by Descartes, who regards animals as mere machines, or automata, destitute of a thinking soul, but not of life or feeling. They are automata, but living and feeling automata. Descartes denies them a soul, because he defines the soul as the thinking and knowing power. But Locke (with whom Leibnitz fully agreed on this point) ascribes to animals thought as well as feeling, and makes their difference from man to consist in their not possessing abstract ideas. We shall presently see the truth of this most sagacious remark.
Plants, animals, and men are alike in possessing the vital principle, which produces growth, which causes them to pass through regular phases of development, which enables them to digest and assimilate food taken from without, and which carries on a steady circulation within. To this are added, in the animal, the function of voluntary locomotion, perception through the senses of an outward world, the power of feeling pleasure and pain, some wonderful instincts, and some degree of reflective thought. Animals also possess memory, imagination, playfulness, industry, the sense of shame, and many other very human qualities.
Take, for example, Buffon's fine description of the dog ("Histoire du Chien"):—
"By nature fiery, irritable, ferocious, and sanguinary, the dog in his savage state is a terror to other animals. But domesticated he becomes gentle, attached, and desirous to please. He hastens to lay at the feet of his master his courage, his strength, and all his abilities. He listens for his master's orders, inquires his will, consults his opinion, begs his permission, understands the indications of his wishes. Without possessing the power of human thought, he has all the warmth of human sentiment. He has more than human fidelity, he is constant in his attachments. He is made up of zeal, ardor, and obedience. He remembers kindness longer than wrong. He endures bad treatment and forgets it—disarming it by patience and submission."
No one who has ever had a dog for a friend will think this description exaggerated. If any should so consider it, we will cite for their benefit what Mr. Jesse, one of the latest students of the canine race, asserts concerning it, in his "Researches into the History of the British Dog" (London, 1866). He says that remarkable instances of the following virtues, feelings, and powers of mind are well authenticated:—
"The dog risks his life to give help; goes for assistance; saves life from drowning, fire, other animals, and men; assists distress; guards property; knows boundaries; resents injuries; repays benefits; communicates ideas; combines with other dogs for several purposes; understands language; knows when he is about to die; knows death in a human being; devotes his whole life to the object of his love; dies of grief and of joy; dies in his master's defense; commits suicide; remains by the dead; solicits, and gives alarm; knows the characters of men; recognizes a portrait, and men after long absence; is fond of praise and sensible to ridicule; feels shame, and is sensible of a fault; is playful; is incorruptible; finds his way back from distant countries; is magnanimous to smaller animals; is jealous; has dreams; and takes a last farewell when dying."