For various reasons, biblical scholars for over two hundred years have argued—persuasively—that Deuteronomy was written much more than forty years after Moses’s time (generally understood to be about 1300 BCE). Actually, that isn’t just a modern theory, but goes back to the early centuries of Christianity, at least as far back (from what I can tell) as the church father Jerome, who lived around the year 400 CE. He mused that someone long after Moses, probably Ezra—who lived in the fifth century BCE—had possibly touched up Deuteronomy.
