Barhebraeus composed over 40 diverse works, most in Syriac, although some are in Arabic. Barhebraeus’ major work in the field of the exact sciences is the Ascent of the Mind (Sullāqā hawnānāyā), a textbook of astronomy and mathematical geography (composed in 1279); it was modeled on Ṭūsī’s Tadhkira and incorporated materials taken from other sources. Other influences include: Severus Sebokht (for earlier Syriac works) [see Nau, p. 106f.] and Bīrūnī’s Kitāb al-tafhīm. According to  Ḥājjī Khalīfa Ibn Abī al-Shukr al-Maghribī composed an epitome of Ptolemy’s Almagest at his behest (Kashf al-ẓunūn, vol. 5, pp. 387, 389). [BEA, H. Takahashi]