When it comes to sexual selection through struggle, no doubt there has been great advantage, and it has produced important effects. This occurs among polygamous and also among non-polygamous animals, and the strong males are certain to secure the largest number of females and, consequently, leave the largest number of offspring. This would, no doubt, through the laws of inheritance, be beneficial in producing animals of greater vigor and more perfect health. But even in this case, the males seem to have little preference for any particular female; and so while the least vigorous ones would leave few, and many no offspring, the least vigorous females would leave nearly as many as the more vigorous ones. Still, through pure-blooded males alone, stockbreeders tell us, herds of cattle can be brought up to a high degree of perfection in three or four generations, even if the females, at the beginning of the experiment, are inferior. The first generation would be half pure blood; the second three-fourths; the third, seven-eighths, and the fourth fifteen-sixteenths, or almost thoroughbred. When it comes to man, however, the case is different. With him sexual selection is more important, and the preference shown by both sexes is very marked. Many women have strong prejudices against marrying men with certain characteristics, and nothing will induce them to such a union. So strong are the desires many of them have for mates with particular qualities, that they prefer to remain single rather than marry one not possessing these qualities. Through this preference, on the whole, the better and those most adapted mate with those most suited to them, and a considerably larger class of physically and mentally inferior ones do not mate at all, or, if they do, leave few offspring. The idiot would stand no chance of securing a mate, although, if left free, he would unite with another idiot, like an animal. Such things have happened, and the offspring were not idiots, as might have been expected; but they were not superior beings. The most deformed in body would, in most cases, unless they had mental traits of a high order to counterbalance them, rarely find mates. Thus, through this agency, some of the poorest specimens of both sexes do not produce offspring, and this raises the standard of the health and ability of the race.