This is a very rare first edition of Farghānī’s best known and most influential work, on Ptolemaic astronomy, dated 3 September 1493. The text is descriptive and non-mathematical, which, along with its clear and well-organised presentation, likely contributed to the text’s popularity. The core of the book is the exposition of the basic concepts of Ptolemy's Almagest. However Farghānī also introduces new material. For example, in chapter 21 he states the distances of the planets from the earth (Ptolemy had only stated the distance of the sun and the moon), and in the next chapter the magnitudes of the planets (Ptolemy again had only given the magnitudes of the sun and the moon). Belfort's career was interrupted twice by political upheavals and war: in his final phase, from 1481 to 1493. He printed scientific and medical works, including commentaries on Avicenna and Mesue. This is one of his last books, and the only one of his to contain illustrations. The beautiful woodcut portrait, which has attracted much attention from historians of art, is in the style of the Ferrara master Cosme Tura.