达尔文《物种起源》：
Generally, the most vigorous males, those which are best fitted for their places in nature, will leave most progeny.
一般地说，最强壮的雄性，最适于它们在自然界中的位置，它们留下的后代最多。
原文：
Sexual selection is, therefore, less rigorous than natural selection. Generally, the most vigorous males, those which are best fitted for their places in nature, will leave most progeny. But in many cases victory depends not so much on general vigour, but on having special weapons, confined to the male sex. A hornless stag or spurless cock would have a poor chance of leaving numerous offspring. Sexual selection, by always allowing the victor to breed, might surely give indomitable courage, length of spur, and strength to the wing to strike in the spurred leg, in nearly the same manner as does the brutal cockfighter by the careful selection of his best cocks.
所以性的选择(性择)不及自然选择激烈。一般地说，最强壮的雄性，最适于它们在自然界中的位置，它们留下的后代最多。但在许多场合，胜利的获得并不全在乎体格的一般强壮，而尤其需要雄性有特别的武器。无角的雄鹿，无距的公鸡，恐怕就少有多量繁殖的机会。性的选择，由于总是战胜者得到繁殖，性的选择，几乎同残忍的斗鸡者精心选择他的最好的公鸡一样，一定会赋予公鸡以不屈不挠的勇气、距的长度以及翅膀拍击距腿的力量。
