It is estimated that at one time no less than one-fifth of the population of Rome was in a condition of compulsory servitude. The number was kept up by birth, by the slave market, and by war. In ancient times, the creditor could sell the family of the debtor; the father also could dispose of his children in the same manner. These barbarous measures, however, were less resorted to as manners grew milder, though the laws permitting them were not repealed until the time of Diocletian. Parents had the legal right to expose their unwelcome children, and whoever chose to take the abandoned infants owned them as slaves; but Trajan granted to such children the perpetual right of claiming their freedom, on condition that they could prove that of their parents. By the ancient law, the slave was nothing but a chattel. He possessed no rights, he had no will of his own, he was not a person, and could not seek protection from the law. Over him his master owned absolute power of life and death. Women slaves were wholly subject to their owner's will. They might be required to bear offspring for the mere sake of increasing their master's number of servants, with absolutely no regard to any sentiment they might cherish relative to such a matter. A slave could not legally marry; and for many centuries no union of that nature was held to have any binding force. When it is considered that a large proportion of the slaves owned by Roman masters were secured as the spoils of war, or by kidnapping, and consequently included many persons of both sexes who were well born and educated, it is seen how peculiarly cruel was slavery in those times.