"In fact, however, ancient and medieval friendship was not only an essential public good, it could also be a much deeper and more meaningful personal relationship than it is today, when it is mostly confined to the private sphere. The Jews of King David’s time tolerated polygamy, and the Mosaic law explicitly permitted a man to divorce his wife. David, like the other Jewish patriarchs, had multiple wives, and was not that close to any of them. Vows to friends could be more binding than marriage vows, lasting not only until death, but binding one’s descendants as well. The security of those vows made friendship potentially the most nourishing personal relationship—in both the public and private spheres—in ancient and medieval cultures."