As a necessary consequence of this slow order of natural growth, the individual is injured when sufficient time for growth is not allowed, or when faculties which should remain latent, slowly storing up strength for the proper time of unfolding, are unduly stimulated or brought forward too soon. The writer above quoted remarks: ‘It is not only a waste of material, but a positive cruelty, to send lads of eighteen or twenty into the field.’[17] The evil effect of undue stimulation to a new function is twofold. The first effect is to divert Nature’s force from the consolidation of faculties already fully formed, and, second, to injure the substantial growth of the later faculty, which is thus prematurely brought forward. Thus the child compelled to carry heavy burdens will be deformed or stunted; the youth weighed down by intellectual labour will destroy his digestion or injure his brain. So, if the faculty which is bestowed as the last work of development, that which requires the longest time and the most careful preparation for its advent--the sexual power--be brought forward prematurely, a permanent injury is done to the individual, which can never be completely repaired. The marked distinction which exists between puberty and nubility should here be noted. It is a distinction based upon the important fact that a work of long-continued preparation takes place in the physical and mental nature, before a new faculty enters upon its complete life. Puberty is the age when those changes have taken place in the child’s constitution, which make it physically possible for it to become a parent, but when the actual exercise of such faculty is highly injurious. This change takes place, as a general rule, from fourteen to sixteen years of age. Nubility, on the other hand, is that period of life when marriage may take place, without disadvantage to the individual and to the race. This period is generally reckoned, in temperate climates, in the man at from twenty-three to twenty-five years of age. About the age of twenty-five commences that period of perfect manly vigour, that union of freshness and strength, which enables the individual to become the progenitor of vigorous offspring. The strong constitution transmitted by healthy parents between the ages of twenty-five and thirty-five indicates the order of Nature in the growth of the human race. The interval between these two epochs of puberty and confirmed virility, is a most important period of rapid growth and slow consolidation. Not only is the lifelong work of the body going on at this time, with much greater activity than belongs to adult life--_i.e._, the work of calorification, nutrition, and all that concerns the maintenance of the body during its unceasing expenditure of mechanical and mental force--but the still more powerful actions of development and growth are being carried on to their last and greatest perfection. Although, as will be shown later, the influences brought to