Preceptions (); Nativities (); Revolution (Transfer) of the Years of Nativities (); Governments (Dynasties) and Sects (); Prediction (Judgement) Based on Conjunctions and Oppositions (); The Sick (); Predictions (Judgements) Based On Constellations (Ṣūr)(); Mashallah's treatise De mercibus (On Prices) is the oldest known scientific work extant in Arabic and the only work of his extant in its original Arabic. Multiple translations into medieval Latin, Byzantine Greek and Hebrew were made. One of Mashallah's most popular works in the Middle Ages was a cosmological treatise This comprehensive account of the cosmos along Aristotelian lines, covers many topics important to early cosmology. Postulating a ten-orb universe it strays from traditional cosmology. Mashallah aimed at the lay reader and illustrated his main ideas with comprehensible diagrams. Two versions of the manuscript were printed: a short version (27 chapters) , and an expanded version (40 chapters) . The short version was translated by Gherardo Cremonese (Gerard of Cremona). Both were printed in Nuremberg, in 1504 and 1549, respectively. This work is commonly abbreviated to . Chaucer's source for his astrolabe treatise Mashallah's treatise on the astrolabe (p 10) is the first known of its kind. Later translated from Arabic into Latin (). The exact source of Geoffrey Chaucer's Treatise on the Astrolabe (1391) in Middle English is undetermined but most of his ‘conclusions’ go back, directly or indirectly, to a Latin translation of Mashallah's work, called . Chaucer's description of the instrument amplifies Mashallah’s, and his indebtedness was recognised by John Selden in 1613 and established by Walter William Skeat. While Mark Harvey Liddell held that Chaucer drew on of John de Sacrobosco for the substantial part of his astronomical definitions and descriptions, the non-correspondence suggests his probable source was another compilation. Skeat's Treatise of the Astrolabe includes a collotype MS facsimile of the Latin version of the second part of Mashallah’s work, which parallels Chaucer's. This is also found in R. T. Gunther's, Chaucer and Messahala on Astrology. De elementis et orbibus was included in Gregor Reisch's (ed. pr., Freiburg, 1503; Suter says the text is included in the Basel edition of 1583). Its contents primarily deal with the construction and usage of an astrolabe. In 1981, Paul Kunitzsch argued that the treatise on the astrolabe long attributed to Mashallah is in fact written by Ibn al-Saffar. Texts & Translations On Conjunctions, Religions, and People was an astrological world history based on