In the Christian society, a "one man one woman" model for the Christian marriage was advocated by Saint Augustine (354–439 AD) with his published letter "The Good of Marriage". To discourage polygamy, he wrote it "was lawful among the ancient fathers: whether it be lawful now also, I would not hastily pronounce. For there is not now necessity of begetting children, as there then was, when, even when wives bear children, it was allowed, in order to a more numerous posterity, to marry other wives in addition, which now is certainly not lawful." (chapter 15, paragraph 17) Sermons from St. Augustine's letters were popular and influential. In 534 AD Roman Emperor Justinian criminalized all but monogamous man/woman sex within the confines of marriage. The Codex Justinianus was the basis of European law for 1,000 years.