And yet there is nothing to show that the marriage regulations of Lycurgus had any real effect on the children of the State. That the early Spartans were a hardy and courageous people is undoubtedly true; but apart from the practice of infanticide, which would necessarily get rid of the weak, their character and conduct can be explained by reference merely to the system of training, both of youth and maidens, which Lycurgus rigidly enforced. Lacedemon was essentially a military republic, and its rulers aimed to breed soldiers, rather than men in the noble sense in which the term "man" is now used. Indeed, there is nothing to show that any compulsory attempt to improve the race has ever been successful, apart from the effect which the destruction of feeble and deformed offspring may have, and the influence of the severe training of those who are allowed to survive. Nevertheless, the human race has vastly improved since its first appearance on the earth, if the teachings of the doctrine of evolution are true and applicable to man as well as to the inferior animals. The passage from the native Australian to the European is a long one, and yet they are supposed to represent a common primitive stock. The steps by which the European has been gradually developed, with his special characteristics, cannot now be traced; but one of the chief agencies to which the result is due is that to which Darwin applied the term, "sexual selection." As natural selection has relation to _adaptation_, and its aim is "the survival of the fittest," so sexual selection has reference to _beauty_, and its object is the perpetuation of the most beautiful, according to the taste of the peoples practicing it. Darwin was the first to point out the importance of sexual selection for certain purposes which, as stated by Professor G. J. Romanes, in his "Darwin and after Darwin,"[28:A] "have no reference to utility or the preservation of life." The latter writer in treating of the subject affirms it is universally admitted that the higher animals do not pair indiscriminately, the members of either sex preferring "those individuals of the opposite sex which are to them most attractive." Many birds and certain mammals clearly display the esthetic sense, which is shown by the former particularly in the adorning of their nests with colored objects; and it is reflected in the personal appearance of the animals themselves. During the pairing season, birds take on their most brilliant plumage, and the males take great pains to exhibit their charms before the females, actively competing with one another in so doing. There is similar rivalry among song birds, who strive to see which can best please the females by their singing.