First, there is the rise of the evolution theory, which teaches that there is no absolute break between man and the higher animals in the matter of mental endowment, and that what difference there is must itself be the result of the laws of mental growth; and the second reason is that the more adequate the science of the human mind has become the more evident has it also become that man himself is more of a machine than had been supposed. Man grows by certain laws; his progress is conditioned by the environment, both physical and social, in which he lives; his mind is a part of the natural system of things. So with the animal. The animal fulfils, as far as he can, the same sort of function; he has his environment, both physical and social; he works under the same laws of growth which man also obeys; his mind exhibits substantially the same phenomena which the human mind exhibits in its early stages in the child. All this means that the animal has as good right to recognition, as a mind-bearing creature, so to speak, as the child; and if we exclude him we should also exclude the child. Further, this also means--what is more important for the science of psychology--that the development of the mind in its early stages and in certain of its directions of progress is revealed most adequately in the animals. _Animal Instinct._--Turning to the animals, the first thing to strike us is the remarkable series of so-called animal Instincts. Everybody knows what animal instincts are like; it is only necessary to go to a zooelogical garden to see them in operation on a large scale. Take the house cat and follow her through the life of a single day, observing her actions. She washes her face and makes her toilet in the morning by instinct. She has her peculiar instinctive ways of catching the mouse for breakfast. She whets her appetite by holding back her meal possibly for an hour, in the meantime playing most cruelly with the pitiful mouse, letting it run and catching it again, and doing this over and over. If she has children she attends to their training in the details of cat etiquette and custom with the utmost care, all by instinct; and the kittens instinctively respond to her attentions. She conducts herself during the day with remarkable cleanliness of life, making arrangements which civilized man follows with admiration. She shows just the right abhorrence of water for a creature that is not able to swim. She knows just what enemies to fly from and when to turn and fight, using with inborn dexterity her formidable claws. She prefers nocturnal excursions and sociabilities, having eyes which make it safe to be venturesome in the dark. She has certain vocal expressions of her emotions, which man in vain attempts to eradicate with all the agencies of domestication. She has special arts to attract her mate, and he in turn is able to charm her with songs which charm nobody else. And so on, almost _ad infinitum_.