Islamic Reactions to Ptolemy’s Imprecisions

Abstract

Consider the following quotation from the author of the treatise Fī sanat al-shams (“On the Solar Year”), most likely written in Baghdad in the first part of the ninth century: Ptolemy, in persuading himself that the period of the solar year should be taken according to points on the ecliptic, also persuaded himself as to the observations themselves and did not in reality perform them; coming from his imagination, this was of the greatest harm for what was described for the calculations (Morelon 1987, p. 61; my translation).