Side by side with the body the mind is developed by a taste for reflection, and is finally prepared for studies of a higher order. With this period childhood ends and youth begins.
Although up to the beginning of youth life is, on the whole, a period of weakness, there is a time during this earlier age when our strength increases beyond what our wants require, and the growing animal, still absolutely weak, becomes relatively strong. His wants being as yet partly undeveloped, his present strength is more than sufficient to provide for those of the present. As a man, he would be very weak; as child, he is very strong.
Whence arises this weakness of ours but from the inequality between our desires and the strength we have for fulfilling them? Our passions weaken us, because the gratification of them requires more than our natural strength.
If we have fewer desires, we are so much the stronger. Whoever can do more than his wishes demand has strength to spare; he is strong indeed. Of this, the third stage of childhood, I have now to speak. I still call it childhood for want of a better term to express the idea; for this age, not yet that of puberty, approaches youth.
At the age of twelve or thirteen the child's physical strength develops much faster than his wants. He braves without inconvenience the inclemency of climate and seasons, scarcely feeling it at all. Natural heat serves him instead of clothing, appetite instead of sauce. When he is drowsy, he lies down on the ground and falls asleep. Thus he finds around him everything he needs; not governed by caprices, his desires extend no farther than his own arms can reach. Not only is he sufficient for himself, but, at this one time in all his life, he has more strength than he really requires.
What then shall he do with this superabundance of mental and physical strength, which he will hereafter need, but endeavor to employ it in ways which will at some time be of use to him, and thus throw this surplus vitality forward into the future? The robust child shall make provision for his weaker manhood. But he will not garner it in barns, or lay it up in coffers that can be plundered. To be real owner of this treasure, he must store it up in his arms, in his brain, in himself. The present, then, is the time to labor, to receive instruction, and to study; nature so ordains, not I.