In the mid–seventh century, he wrote extensively on cosmography, on the causes of eclipses, and on geometry and arithmetic: he offers a classic account of the astrolabe. He also wrote commentaries on Aristotle’s logic, translating the Analytics. Like Bishop Elijah, he was very proud of the Syriac achievement, claiming that the Greeks had taken all they knew from the Chaldeans, whom everyone knew to be really Syrians.
