The mechanical methods of reaction which are so prominent low down in the animal scale fill quite a minor place in human life. The ordinary operations of the body, indeed, go upon their way mechanically enough. In walking or in running, in saving ourselves from a fall, in coughing, sneezing, or swallowing, we react as mechanically as do the lower animals; but in the distinctly human modes of behavior, the place taken by the inherited structure is very different. Hunger and thirst no doubt are of the nature of instincts, but the methods of satisfying hunger and thirst are acquired by experience or by teaching. Love and the whole family life have an instinctive basis, that is to say, they rest upon tendencies inherited with the brain and nerve structure; but everything that has to do with the satisfaction of these impulses is determined by the experience of the individual, the laws and customs of the society in which he lives, the woman whom he meets, the accidents of their intercourse, and so forth. Instinct, already plastic and modifiable in the higher animals, becomes in man a basis of character which determines how he will take his experience, but without experience is a mere blank form upon which nothing is yet written. For example, it is an ingrained tendency of average human nature to be moved by the opinion of our neighbors. This is a powerful motive in conduct, but the kind of conduct to which it will incite clearly depends on the kind of thing that our neighbors approve. In some parts of the world ambition for renown will prompt a man to lie in wait for a woman or child in order to add a fresh skull to his collection. In other parts he may be urged by similar motives to pursue a science or paint a picture. In all these cases the same hereditary or instinctive element is at work, that quality of character which makes a man respond sensitively to the feelings which others manifest toward him. But the kind of conduct which this sensitiveness may dictate depends wholly on the social environment in which the man finds himself. Similarly it is, as the ordinary phrase quite justly puts it, "in human nature" to stand up for one's rights. A man will strive, that is, to secure that which he has counted on as his due. But as to what he counts upon, as to the actual treatment which he expects under given circumstances, his views are determined by the "custom of the country," by what he sees others insisting on and obtaining, by what has been promised him, and so forth. Even such an emotion as sexual jealousy, which seems deeply rooted in the animal nature, is largely limited in its exercise and determined in the form it takes by custom. A hospitable savage, who will lend his wife to a guest, would kill her for acting in the same way on her own motion. In the one case he exercises his rights of proprietorship; in the other, she transgresses them. It is the maintenance of a claim which jealousy