However, in addition to the sense of sight, the sense of hearing plays a part of considerable importance in the amatory life of mankind. A sufficient indication of this fact is given by the change occurring in a man’s voice at the time of puberty. Darwin’s classical investigations prove beyond a possibility of doubt the intimate relationship between the voice and sexual life. The masculine voice, especially, has a sexually stimulating effect upon woman; but the converse influence of a woman’s voice upon man may also be observed. In the other mammalia, it is especially in the rutting season that the voice is used as a means of sexual allurement. The repetition of this vocal lure at measured intervals gives rise to rhythm and song. The rhythmical repetition of the same tone possesses something highly suggestive, fascinating, and so gives rise to sexual attraction and charm in the most powerful manner. Here lies the origin of the profound erotic influence of singing and music. Darwin assumes that the early progenitors of mankind, before they had acquired the faculty of expressing their mutual love in articulate speech, used to charm one another by musical tones and rhythms. Woman is far more susceptible than man to the sexual influence of singing or music, but man himself is by no means indifferent to the charms of the beautiful feminine voice. The soft tones of a woman’s voice are, for many men, the first enthralling disclosure of woman’s nature. The French physician and natural philosopher Moreau relates that he was once compelled to renounce the pleasure of seeing the performance of a beautiful actress, for only thus could he overcome a violent outburst of sexual passion which was evoked in him by the mere stimulus of her voice. [4] If at the present day an inquiry were instituted among the cultured women of European and Anglo-American descent, whether bearded or beardless men more nearly corresponded to their ideal of beauty, there can be little doubt that the majority--perhaps a very large majority--would declare against a full beard.