According to oriental tradition, Mahomet married Khadijah when five years of age, and cohabited with her three years later. In the Bible, numerous similar examples are recorded. Among many savage tribes, as, for instance, among some of the aborigines of India, and among the indigens of Australia, copulation is usually effected before girls reach the age of puberty; in India, indeed, according to _Ploss_ and _Bartels_ (_Das Weib in der Natur und Völkerkunde_), marriage with immature girls is a widely diffused custom, and in Australia a child of ten or eleven is often found to be the wife of a man of fifty or the concubine of a sailor. In general, according to these authors, we find that the age of nubility in girls is lower in proportion to the lowness of the stage of civilization attained by the race or people to which they belong. Among the ancient Romans, girls were commonly married between the ages of thirteen and sixteen years. In the Talmud, _Rabbi Joshua_ gives the following advice regarding early marriage in Jewish girls: “If your daughter has attained puberty and is twelve years and six months old, she must be married at any cost. If no other means are available, manumit one of your slaves, and give her to the freedman to wife.” Experience proves, however, that in our climate, at any rate, girls who marry at a very early age are inferior in fertility to those who refrain from marriage until the genital organs have attained complete maturity; and statistics show that those women who marry before attaining the age of twenty must wait longer for their first pregnancy than those who marry between the ages of twenty and twenty-four. At the higher age also, women bear parturition and its consequences more easily than those who marry very young. A similar influence in marriage to that resulting from undue juvenility is exercised by its opposite, marriage when a woman is already elderly; in this case fertility is limited, and health also is especially apt to suffer. When the indications of the climacteric are clearly apparent, marriage is contra-indicated, not only on account of the impossibility of fertilization, but also in respect of its general unsuitability in the closing stage of the sexual life.