It is in the application of the principle of sexual selection to the mental characteristics of man, that any real improvement of the race, viewed as consisting of human beings and not of mere animals, must be brought about. Beauty of physical form and feature is of importance in human relations only so far as it is associated with beauty of mind and character, that is, with high intellectual and moral attainments. That these often go together is true, but it is not always the case. Grant Allen says: "To be sound in wind and limb; to be healthy of body and mind; to be educated; to be emancipated; to be free, to be beautiful--these things are ends towards which all should strive, and by attaining which all are happier in themselves, and more useful to others." But physical and intellectual perfection are not always found together, as was observed by Darwin, when he mentioned among the causes which interfere with the physical action of sexual selection the fact that men are largely attracted by the mental charms of women. Professor Jowett affirms truly that "Many of the noblest specimens of the human race have been among the weakest physically. Tyrtaens or AEsop, or our own Newton, would have been destroyed at Sparta, and some of the fairest and strongest men and women have been among the wickedest and worst." Hence, he properly infers that "Not by the Platonic device of uniting the strong and the fair with the strong and the fair, regardless of sentiment and morality, nor yet by his other device of combining dissimilar natures, have mankind gradually passed from the brutality and licentiousness of primitive marriage to marriage Christian and civilized."