The advice to marry young, which is in every respect socially wise and physiologically correct for some, should not be hurled indiscriminately at all women, because for the late maturing such advice is socially disadvantageous and physiologically wrong. I am now ready to consider the question of the proper age for motherhood about which an immense variety of opinion is expressed. The general tendency has been, even in the last few years, to raise the age at which a girl may marry, and to raise the age which the medical profession advises as the earliest suitable for motherhood. But still one often hears of elders, whom one would in other respects like to follow, advising the early bearing of children. Now I should like every potential parent to consider what type of child they want. Do they want to secure healthy, jolly little animals with no more brains than are sufficient to see them creditably through life? If so, let them have their children very early. Such healthy sound people with no special gifts are valuable, and there is much work in the world for them to do. On the other hand, do they want to take the risk for their child of a possibly less robust body, but with the possibility, indeed, in healthy families, almost the certainty, of an immensely greater brain power, and a more strongly developed temperament? Then let them have their children late. And if a man desires to have a child who may become one of the _master_ minds whose discoveries, whose artistic creations, whose ruling power stamps itself upon the memory of our race, whose name is handed down the ages, then let the father who desires such a child mate himself with the long-young late-maturing type of woman I have just described, and let her bear that child some time between the age of thirty-five and forty-five. How often one hears some version of the phrase: “Yes, it is so sad, poor, dear Lord So-and-So, a charming man, but no brains at all; his younger brother such a brilliant man; but that is always the way, the eldest sons in the aristocracy do seem to get the gift of property balanced by the lack of brains.” Now I enquire, and I should like my readers to enquire, into the secret of this phenomenon, which is by no means universal, but is sufficiently common to be endorsed. In my opinion, the interpretation of this fact is that the earlier children were born when the mother was still too young to endow them with brains, particularly if the mother was one of the gifted and cultivated women of the late-maturing type.