demonstrate the natural reality of the 12 signs by stressing that the stars are located with respect to the signs and that fundamental natural phenomena, such as the beginning of the seasons, changes of weather, and the passage of the months, take place in the sublunar domain when the sun enters the signs of the ninth orb . Mashallah was an advocate of the idea that the conjunctions of Saturn and Jupiter dictate the timing of important events on Earth. These conjunctions, which occur about every twenty years, take place in the same triplicity for about two hundred years, and special significance is attached to a shift to another triplicity. Bibliography De cogitatione Epistola de rebus eclipsium et conjunctionibus planetarum (distinct from De magnis conjunctionibus by Abu Ma'shar al Balkhi ; Latin translation : John of Sevilla Hispalenis et Limiensis De revolutionibus annorum mundi De significationibus planetarum in nativitate Liber receptioni Works of Sahl and Masha'allah, trans. Benjamin Dykes, Cazimi Press, Golden Valley, MN, 2008. Masha'Allah, On Reception, trans. Robert Hand, ARHAT Publications, Reston, VA, 1998. See also Liber de orbe Astrology in medieval Islam Jewish views of astrology List of Persian scientists and scholars References Footnotes Citations Bibliography External links (PDF version) Blog, History of Science Collections, University of Oklahoma Libraries Pseudo-Masha’Allah, On the Astrolabe, ed. Ron B. Thomson, version 1.0 (Toronto, 2012); A Critical Edition of the Latin Text with English Translation by Ron B. Thomson. 8th-century births 810s deaths 8th-century Arabic writers 8th-century astrologers 8th-century Iranian astronomers 8th-century Jews 8th-century Iranian mathematicians 9th-century Iranian astronomers 9th-century Jews 9th-century astrologers 9th-century Arabic writers Astronomers from the Abbasid Caliphate Astronomers of the medieval Islamic world Jewish astronomers Court scholars Jews from the Abbasid Caliphate Medieval Jewish astrologers Medieval Jewish astronomers People from Basra Medieval Iranian astrologers Medieval Persian Jews 9th-century Iranian mathematicians 8th-century people from the Abbasid Caliphate 9th-century people from the Abbasid Caliphate