But if it is difficult to believe that the display of the males could call forth an intellectual activity in the hen, such as that of comparing and valuing the merits of the rival suitors,[273] one can safely assume that it might influence her emotional and instinctive life. And for the production of such an effect there is no need to suppose any intervening æsthetic activity. Considering the close parallelism which shows itself in the development of either sex, it would only be natural if a colour and voice alteration in the cock, which undeniably is dependent upon sexual ripening,[274] should directly and almost physiologically imply a reaction in the sexual life of the hen. The more energetically the male forces himself upon the attention of the female by the conspicuous visual and acoustic signs of his sex, the more powerful must necessarily be the emotional response in her. If secondary sexual characters are interpreted in this way, as signs, by which the sex of the male is manifested in an unmistakable manner, then one can easily understand the influence of a prolonged display. When the cock is exhibiting his plumes or pouring forth his notes, and thereby impressing upon his female listener the notion of his malehood, he cannot but produce in her an enhanced inclination for pairing.[275] She needs no æsthetic appreciation or intellectual judgment in order to comprehend the simple text of all his utterances. With all her instincts and impulses she can at once grasp the only thing she wants to know—the thing that is brought home to her with a greater and greater clearness during the continuation of his performance, namely, that the passionate actor in front of her is a mature representative of the other sex. And besides this, the secondary sexual characters and activities tell another tale of no less importance. If the colours and the tones of the cock, as Westermarck has shown, are of great consequence for facilitating from a distance recognition between members of the same species,[276] their biological significance is perhaps yet greater when they, during the display before the hen, accentuate the community of species. By virtue of her inherited constitution, the instinctive life of the hen will be deeper stirred the more the male is able to show that he “wears the feathers of her tribe.”