This interval in which the strength of the individual is in excess of his wants is, as I have said, relatively though not absolutely the time of greatest strength.  It is the most precious time in his life; it comes but once; it is very short, all too short, as you will see when you consider the importance of using it aright.

He has, therefore, a surplus of strength and capacity which he will never have again.  What use shall he make of it?  He will strive to use it in tasks which will help at need.  He will, so to speak, cast his present surplus into the storehouse of the future; the vigorous child will make provision for the feeble man; but he will not store his goods where thieves may break in, nor in barns which are not his own.  To store them aright, they must be in the hands and the head, they must be stored within himself.  This is the time for work, instruction, and inquiry.  And note that this is no arbitrary choice of mine, it is the way of nature herself.

Human intelligence is finite, and not only can no man know everything, he cannot even acquire all the scanty knowledge of others.  Since the contrary of every false proposition is a truth, there are as many truths as falsehoods.  We must, therefore, choose what to teach as well as when to teach it.  Some of the information within our reach is false, some is useless, some merely serves to puff up its possessor.  The small store which really contributes to our welfare alone deserves the study of a wise man, and therefore of a child whom one would have wise.  He must know not merely what is, but what is useful.

From this small stock we must also deduct those truths which require a full grown mind for their understanding, those which suppose a knowledge of man’s relations to his fellow-men—­a knowledge which no child can acquire; these things, although in themselves true, lead an inexperienced mind into mistakes with regard to other matters.

We are now confined to a circle, small indeed compared with the whole of human thought, but this circle is still a vast sphere when measured by the child’s mind.  Dark places of the human understanding, what rash hand shall dare to raise your veil?  What pitfalls does our so-called science prepare for the miserable child.  Would you guide him along this dangerous path and draw the veil from the face of nature?  Stay your hand.  First make sure that neither he nor you will become dizzy.  Beware of the specious charms of error and the intoxicating fumes of pride.  Keep this truth ever before you—­Ignorance never did any one any harm, error alone is fatal, and we do not lose our way through ignorance but through self-confidence.