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:--