For while, where the intellect is highly cultured, and the cerebral life composes the major activity of the individual, early marriage becomes generally the most dangerous of all experiments, and the fruitful cause of human anguish, or the yet more disastrous cause of human atrophy and non-development, it may, on the other hand, lose all its danger where the intellectual faculties are more or less dormant through non-cultivation, and where the action of the physical functions form the major activity of the individual concerned. For, while the brain, in the mentally labouring individual often continues to grow and modify itself till forty, or in exceptional cases till much later, and while the psychic condition in the case of such persons tends completely to modify and change itself between the age of adolescence and the ripe adult maturity of thirty or thirty-five--so that the man or woman of thirty-three has often little or nothing in common with the youth or maiden of eighteen, or even of twenty-one, out of whose crude substance they have developed; and who therefore may have little or nothing in common with the individual whom that youth or maiden selected as a companion, and may therefore find, long before middle life, the continual union with that individual a moral deformity and a mental death--it is, on the other hand, probable that where the brain is not highly active, and under conditions of life in which (however great the natural intelligence) the intellectual faculties are kept more or less quiescent, where little mental stimulation is brought to bear on the individual between the ages of puberty and ripe adulthood, that little or no change or development takes place; and that therefore the person who is selected as an appropriate companion at eighteen or twenty-one will probably be quite as harmonious a companion at thirty or forty; and the danger of early marriage is non-existent.