The relationship between the expansion of literacy in Judah and composition of biblical texts has attracted scholarly attention for over a century. Information on this issue can be deduced from Hebrew inscriptions from the final phase of the first Temple period. We report our investigation of 16 inscriptions from the Judahite desert fortress of Arad, dated ca. 600 BCE-the eve of Nebuchadnezzar's destruction of Jerusalem. The inquiry is based on new methods for image processing and document analysis, as well as machine learning algorithms. These techniques enable identification of the minimal number of authors in a given group of inscriptions. Our algorithmic analysis, complemented by the textual information, reveals a minimum of six authors within the examined inscriptions. The results indicate that in this remote fort literacy had spread throughout the military hierarchy, down to the quartermaster and probably even below that rank. This implies that an educational infrastructure that could support the composition of literary texts in Judah already existed before the destruction of the first Temple. A similar level of literacy in this area is attested again only 400 y later, ca. 200 BCE. B ased on biblical exegesis and historical considerations scholars debate whether the first major phase of compilation of biblical texts in Jerusalem took place before or after the destruction of the city by the Babylonians in 586 BCE (e.g., ref. 1). A related-and also disputed-issue is the level of literacy, that is, the basic ability to communicate in writing, especially in the Hebrew kingdoms of Israel and Judah (2). The best way to answer this question is to look at the material evidence: the corpus of inscriptions that originated from archaeological excavations (e.g., ref.3). Inscriptions citing biblical texts, or related to them, are rarely found (for two Jerusalem amulets possibly dating to this period, echoing the priestly blessing in Numbers 6:23-26, see refs. 4 and 5), probably because papyrus and parchment are not well preserved in the climate of the region. However, ostraca (inscriptions in ink on ceramic sherds) that deal with more mundane issues can also shed light on the volume and quality of writing and on the recognition of the power of the written word in the society.To explore the degree of literacy and stage setting for compilation of literary texts in monarchic Judah, we turned to Hebrew ostraca from the final days of the kingdom, before its destruction by Nebuchadnezzar in 586 BCE and the deportation of its elite to Babylonia. Several corpora of inscriptions exist for this period. We focused on the corpus of over 100 Hebrew ostraca found at the fortress of Arad, located in arid southern Judah, on the border of the kingdom with Edom (see ref. 6 and Fig.
