What busy tumult among those older boys at the brook down yonder! They have built canals and sluices, bridges and seaports, dams and mills, each one intent only on his own work. Now the water is to be used to carry vessels from the higher to the lower level, but at each step of progress one trespasses on the limits of another realm, and each one equally claims his right as lord and maker, while he recognizes the claims of the others. What can serve here to mediate? Only treaties, and, like states, they bind themselves by strict treaties. Who can point out the varied significance, the varied results, of this play of boys? Two things, indeed, are clearly established which proceed from this spirit of boyhood: the playing boys will make good pupils, intelligent and quick to learn, quick to see and to do, diligent and full of zeal, reliable in thought and feeling, efficient and vigorous; and those who have played thus are efficient men, or will become so.

The inventor of kindergarten explains the importance of free play for a child’s development.