So it is with these human instincts. They arise at early adolescence; they die down with the passing of youth. Meanwhile, they tend to develop into persistent habits of mind. Whether they shall so develop, and which shall persist and which die away, depends on the boys’ surroundings and education. Consider, for example, the special human instinct which we share with only a few of the brutes, the instinct of acquisitiveness. It is the basis of most of our adult frugality, and of the institution of private property. Too little of it makes us spendthrifts; too much makes us misers and kleptomaniacs; with just the right amount we become solid citizens and taxpayers. Unquestionably, acquisitiveness is instinctive in boys; witness the contents of their pockets, and their collections of all sorts of useless truck. They steal things to eat and to provision their camps, with about as much attention to the morals of their acts as the squirrel who secretes nuts or the dog who buries his bone. They are continually appropriating articles which they cannot possibly use, merely for the sake of possessing them. It was a wise mother and a good psychologist who, when her cake became too dry to put upon the table, used to “hide it away for the children to steal.” In the adolescent boy this entirely natural instinct usually shows itself as a desire to steal, which is normal but not proper. On the whole, the gang does encourage stealing; forty-nine of our sixty-six gangs report this form of predatory activity. We all did it as boys, and most of us have grown up to be fairly honest men. For there seem to be inherent forces in the gang itself that tend to check stealing. For one thing, both example and emulation among the members of a gang reinforce the impulse to form collections of shells, postage stamps, butterflies or minerals, and these in a natural and wholesome fashion satisfy the acquisitive instinct and turn it away from theft. The common property of the gang, too, its wood hut or clubroom with their furnishings, the bats and balls and other common tools of the gang probably act in the same way. Doubtless, too, the boys’ grief when a hostile gang wrecks their property or runs off with their bats and balls reinforces powerfully the law of _meum et tuum_. Certain it is that experienced educators regard as vastly more serious the case of the lad who goes off to steal by himself for his own profit than that of the one who steals in company with his fellows and for the advantage of the gang.