A German scientist, Dr. Vaerting, of Berlin, published on the eve of the War a little book on the most favourable age in parents for the production of children of ability (_Das guenstigste elterliche Zeugungsalter_).[1] He approaches the question entirely in this new spirit, not as a merely academic topic of discussion, but as a practical matter of vital importance to the welfare of society. He starts with the assertion that "our century has been called the century of the child,"[2] and for the child all manner of rights are now being claimed. But the prime right of all, the right of the child to the best ability that his parents are able to transmit to him, is never even so much as considered. Yet this right is the root of all children's rights. And when the mysteries of procreation have been so far revealed as to enable this right to be won, we shall, at the same time, Dr. Vaerting adds, renew the spiritual aspect of the nations. The most easily ascertainable and measurable factor in the production of ability, and certainly a factor which cannot be without significance, is the age of the parents at the child's birth. It is this factor with which Vaerting is mainly concerned, as illustrated by over one hundred German men of genius concerning whom he has been able to obtain the required data. Later on, he proposes to extend the inquiry to other nations. Vaerting finds--and this is probably the most original, though, as we shall see, not the most unquestionable of his findings--that the fathers who are themselves of no notable intellectual distinction have a decidedly more prolonged power of procreating distinguished children than is possessed by distinguished fathers. The former, that is to say, may become the fathers of eminent children from the period of sexual maturity up to the age of forty-three or beyond. When, however, the father is himself of high intellectual distinction, Vaerting finds that he was nearly always under thirty, and usually under twenty-five years of age at his distinguished son's birth, although the proportion of youthful fathers in the general population is relatively small. The eleven youngest fathers on Vaerting's list, from twenty-one to twenty-five years of age, were (with one exception) themselves more or less distinguished, while the fifteen oldest, from thirty-nine to sixty years of age, were all without exception undistinguished. Among these sons are to be found much greater names (Goethe, Bach, Kant, Bismarck, Wagner, etc.) than are to be found among the sons of young and more distinguished fathers, for here there is only one name (Frederick the Great) of the same calibre. The elderly fathers belonged to large cities and were mostly married to wives very much younger than themselves. Vaerting notes that the most eminent geniuses have most frequently been the sons of fathers who were not engaged in intellectual avocations at all, but earned their livings as simple craftsmen.