His geometrical work entitled Ashkāl al-ta’sīs contains 35 propositions from Euclid’s Elements; the first 30 propositions are strictly geometrical, while the last 5 deal with what has been called “geometrical algebra.” Regarding the problem of the fifth (“parallels”) postulate, he supported Euclid and considered the criticisms of earlier Islamic mathematicians to have been misplaced. The most important aspect of the book was Samarqandī’s view that a study of geometry was a propaedeutic to the study of the forms of Platonic philosophy. It was taught as a “middle-level” textbook for Muslim scholars in the madrasas, later most often with Qāḍīzāde’s Sharḥ [BEA, Fazlioglu]