De revolutionibus orbium coelestium have begun work on his new system by that time. Most historians believe that he wrote the "Commentariolus" after his return from Italy, possibly only after 1510. At this time, Copernicus anticipated that he could reconcile the motion of the Earth with the perceived motions of the planets easily, with fewer motions than were necessary in the "Alfonsine Tables", the version of the Ptolemaic system current at the time. In particular, the heliocentric Copernican model made use of the Urdi Lemma developed in the 13th century by Mu'ayyad al-Din al-'Urdi, the first of the Maragha astronomers to develop a non-Ptolemaic
Christianity in the 16th century the Reformed church in Geneva, which became an "unofficial capital" of Reformed Christianity in the second half of the 16th century. He exerted a remarkable amount of authority in the city and over the city council, such that he has (rather ignominiously) been called a "Protestant pope." Calvin established an eldership together with a consistory, where pastors and the elders established matters of religious discipline for the Genevan population. Calvin's theology is best known for his doctrine of (double) predestination, which held that God had, from all eternity, providentially foreordained who would be saved (the elect) and likewise who would