Scholarly shorthand for the author of Deuteronomy, the fourth source in the Pentateuch. D depicts Moses giving a series of speeches, which urge Israel to follow the “torah.” But the law of which Moses speaks represents a massive revision of earlier laws. Among the Pentateuchal sources (J, E, D, and P), D is unique in mandating the centralization of the Yahwistic cult and the suppression of all Canaanite cults (Deut. 12).

Most scholars believe that Deuteronomy achieved its final form as the result of a long process of composition. Since the nineteenth century CE, they have identified “the book of the law” (2 Kings 22.8) discovered during the eighteenth year of Josiah's reign (ca. 621 BCE) as an early form of Deuteronomy. The books of Kings mention other reformers (e.g., Hezekiah, 2 Kings 18.4), but Josiah's exhaustive reforms and national Passover (2 Kings 23.4–23) explicitly conform to Deuteronomic prescriptions. Hence, dating the substance of the D source (i.e., the laws in Deut. 12–26) to the seventh century BCE seems sound. A minority of scholars view the description of Josiah's reforms as a utopian projection and date D to the exilic or early postexilic age (mid‐ to late sixth century).

Gary N. Knoppers