Hesiod, Works and Days, II, 690-700.
This has long been the accepted opinion of medical authorities, as may be judged by the statements brought together two centuries ago by Schurig, Parthenologia, pp. 22-25.
The statement that, on the average, the best age for procreation in men is before, rather than after, forty, by no means assumes the existence of any "critical" age in men analogous to the menopause in women. This is sometimes asserted, but there is no agreement in regard to it. Restif de la Bretonne (Monsieur Nicolas, vol. x, p. 176) said that at the age of forty delicacy of sentiment begins to go. Fürbringer believes (Senator and Kaminer, Health and Disease in Relation to Marriage, vol. i, p. 222) that there is a decisive turn in a man's life in the sixth decade, or the middle of the fifth, when desire and potency diminish. J. F. Sutherland also states (Comptes-rendus Congrès International de Médecine, 1900, Section de Psychiatrie, p. 471) that there is, in men, about the fifty-fifth year, a change analogous to the menopause in women, but only in a certain proportion of men. It would appear that in most men the decline of sexual feeling and potency is very gradual, and at first manifests itself in increased power of control.