Introduction

Levi ben Gerson (1288–1344), sometimes called Gersonides or Leo de Balneolis, is well known as a philosopher, biblical exegete, mathematician, and astronomer (cf. Touati, 1973; and Feldman, 1984). He lived in Orange and occasionally visited Avignon where his brother Solomon was physician to Pope Clement VI. Although the family name was de Balneolis, there is no evidence that he himself was born or ever lived in Bagnols (cf. Shatzmiller, 1972, 1974). Levi did not cite any contemporaries and little is known of his life. More surprisingly, his scientific work was rarely cited in the subsequent literature, though a number of manuscript copies survive both in the original Hebrew and in Latin translations. The works on which Levi depended were all available in Hebrew and there is no reason to believe he read astronomical texts in Latin or in Arabic. A recent article has brought attention to a list of the books in Levi’s library that had not been properly identified in the manuscript catalogue (Weil, 1980, p. 590; cf. Loewinger and Weinryb, 1965, p. 32). Many of the 140 items concerned astronomy and, judging from the incomplete published list, they were all in Hebrew.