Augustine of Hippo : WIVES AND CONCUBINES. — Among the women named in Scripture, wives are not easily distinguished from concubines. For Hagar is called a wife, and later she is called a concubine, as well as Keturah (Gen. 16:3); also Rachel and Leah gave slaves to their husbands (Gen. 30:3-4, 9). According to the usual language of Scripture, a concubine may be called a wife, but not every wife is called a concubine. That is to say, Sarah, Rebekah, Leah and Rachel cannot be called concubines. On the other hand, Hagar, Keturah, Bala and Zelfa can be called wives and concubines. [ — QUESTIONS ON GENESIS, Q. 89 (tr. J. Litteral, draft)