In order that an intelligent creature should be evolved it was necessary that instinct should become plastic. Intelligence could not be superposed upon a complete and final instinctive equipment. You cannot determine your own acts if they are already determined for you by your nervous organisation. The incomparable superiority of intelligence depends upon its limitless and creative character, in virtue of which, as Disraeli puts it, “men are not the creatures of circumstances: circumstances are the creatures of men.” But whilst intelligence can learn everything, it has everything to learn, and the most nearly intelligent creature whom the earth affords thus begins his independent life almost wholly bereft of all the instruments which have served the lower creatures so well, whilst, on the other hand, he is provided with an utterly undeveloped, and indeed, at that time non-existent, weapon which, even if it did exist, he could not use. Hence the unique helplessness of the human baby: one of the most wonderful and little appreciated facts in the whole of nature--effectively hidden from the glass eyes of the kind of man who calls a baby a “brat,” but, to eyes that can see, not only the master paradox from the philosophical point of view but also a fact of the utmost moment from the practical point of view. =The evolution of motherhood.=--It directly follows that motherhood is supremely important in the case of man. It is the historical fact that its importance in the history of the animal world has been steadily increasing throughout æonian time. The most successful and ancient societies we know, those of the social insects, which antedate by incalculable ages even the first vertebrates, could not survive for a single generation without the motherhood or foster-motherhood to which the worker females sacrifice their lives and their own chances of physical maternity. The development of maternal care may be steadily traced throughout the vertebrate series--_pari passu_ with the evolution of sexual relations towards the ideal of monogamy, which is ideal just because of its incomparable services to motherhood. But whilst motherhood is of the utmost service for lower creatures, tending always to lessen infant mortality--if it may be so called--and to increase the proportion of life to death and birth, it is of supreme service in the case of man because of the absolute dependence upon it of intelligence, the solitary but unexampled weapon with which he has won the earth. Hence in breeding for intelligence we cannot afford to ignore that upon which intelligence depends. Even if we could produce genius at will, we should find our young geniuses just as dependent upon motherhood as the common run of mankind. Newton himself was a seven months' baby, and the potentialities of gravitation and the calculus and the laws of motion in his brain could not save him: motherhood could and did.