There is abundant evidence that the mental and moral capacities are inherited in the same way as the purely physical or physiological ones. We have, however, much more to learn about how to control the development of the former than about the control of the latter. Yet this point should be clear to every parent and teacher; whatever the child's inheritance may be, the full development of his capacities is possible only under suitable external conditions. What these conditions are depends upon the combination of capacities that the particular child possesses. But to find out what these capacities are we must give the child an opportunity to show "what's in him." This we can do by placing him in an environment simple enough for him to adjust himself to readily, and at the same time complex enough to give every side of his nature a chance to respond. This is the significance of modern educational movements that seek to leave the child untrammelled in his responses to what goes on around him. We have learned that some children will become tall and that others will never reach beyond a certain height; we seek merely to keep them healthy by suitable feeding, exercise, rest, bathing, etc. But in the matter of mental development we have not yet learned that it is impossible for all children to reach the same degree of linguistic or mathematical or artistic development, and we try to bring all of them up to our preconceived standard of what a child _should_ do in each line. The thing that we need to find out is what a particular child _can_ do; and then we must give him the opportunity and the encouragement to do his best. The things we encourage him to do will be the basis for the habits which he will form, for the skill which he will acquire--and so for the activities that will yield him satisfaction and determine his behavior in relation to others. That is, the things the child learns to do well will determine what kind of a person he will be when he grows up.