At eight or nine the child enters a new period, lasting until puberty. The bodily growth is relatively at rest, but vitality, activity, and the power to resist disease and fatigue show an enormous increase. The age of reason is only dawning, and imitation is yet a strong motive power. “Demonstrate, show, envisage,” and not “explain” is to be the motto. “Children comprehend much and very rapidly if we can only refrain from explaining, but this slows down intuition, tends to make casuists and prigs, and to enfeeble the ultimate vigor of reason. It is the age of little method and much matter” (1: vol. ii, p. 452). A beginning in the fundamentals of all learning and skill which need technicalities is to be made; constant drill in these will form a stable automatic basis of mind. The qualities required of the teacher here are not so much those of the instructor as of “the captain of the boy’s gang.” He or she is to be able to lead, drive, and discipline more than to teach “the human colt, which is by nature in some sense the wildest of all wild animals.” But with the teens there must come a total change in the mode of education. “Powers and faculties, essentially nonexistent before, are now born, and of all the older impulses and instincts some are reënforced and greatly developed, while others are subdued, so that new relations are established and the ego finds a new center” (1: vol. ii, p. 70). The child in the preceding period was well adjusted to his environment; his development was proportionate and relatively slow; and he lived content with himself in his own child world. He thus “represents probably an old and relatively perfected stage of race maturity”; which “stands for a long-continued one, a terminal stage of human development at some post-simian point” (1: vol. ii, p. 71). But with the advent of adolescence, this peaceful, primeval paradise is lost forever. The youth with its all-sided mobilization and with its intense enthusiasm enters into the conquest of a higher kingdom of manhood. The individual is now recapitulating a long viaticum of ascent which the race had to make with heat and ferment, with fight and defeat, before it evolved its historic stage of civilization. “Early adolescence is thus the infancy of man’s higher nature, when he receives from the great all-mother his last capital of energy and evolutionary momentum” (1: vol. ii, p. 71). “It is the most critical stage of life, because failure to mount almost always means retrogression, degeneracy, or fall” (1: vol. ii, p. 72). Indeed, one of the greatest problems of civilization, therefore of education, is how to make “the earlier stages of adolescence ever surer and safer, and its later possibilities ever greater and prolonged.”