This is the Torah's divorce text: a man who finds “some indecency” (Hebrew ervat davar, literally “a matter of nakedness”) in his wife writes her “a bill of divorcement,” the sefer keritut, later called the get: a formal written document whose careful delivery protected the woman's proven right to remarry. What exactly ervat davar covers became the most famous legal dispute of the generation before Jesus, between the two great Pharisaic teaching schools. The Mishnah records it verbatim: the house of Shammai permits divorce only for unchastity; the house of Hillel “even if she spoiled his dish”; Rabbi Akiva, later, “even if he found another fairer than she” (Gittin 9:10).

That standing debate is why the Pharisees' test question in Matthew 19:3, “is it lawful to divorce one's wife for any cause?”, is not a cold question: “for any cause” is the Hillelite position quoted back at Jesus. He is being asked to pick a school. His answer reaches behind Moses to creation itself (Genesis 1:27, 2:24).