An Arabic-Greek Codex of Ptolemy’s Handy Tables from the Eighth Century

Abstract

A Greek copy of Ptolemy’s Handy Tables and an Arabic translation of Theon’s Short Commentary on them survive as undertexts in the palimpsest manuscript Vat. sir. 623. pt. 2. The parchment leaves containing these texts were recycled into a new codex at the Monastery of St. Catherine on Sinai in the late ninth century, but they belonged to the same original manuscript and are considered the only surviving witnesses to the project of translating Greek thought into Arabic at the so-called “House of Wisdom” in Baghdad during the second half of the eighth century. In order to show the importance of this startling discovery made in the Vatican Library, the article not only includes an historical, codicological, and paleographical examination of the erased texts and repurposed folios, but also presents an astronomical explanation of the theories and calculations they contain. The article highlights the list of Greek-Arabic winds and its link to Ptolemy’s Horizon Diagram, as well as stresses the continued applicability of Ptolemy and Theon’s presentations. It further argues for a reconsideration of the meaning of an ancient theory of the “inclinations” that the Sun and the Moon (or the Moon and the Earth’s shadow) create during eclipses, the phenomenon which is called prosneusis.