In 1611, Scheiner observed sunspots; in 1612 he published the ""Apelles letters"" in Augsburg. Mark Welser had the first three "Apelles letters" printed in Augsburg on 5 January 1612. They provided one of many reasons for the subsequent unpleasant argument between Scheiner and Galileo Galilei, which began when Galileo responded to the Apelles letters with his own "Letters on Sunspots". Scheiner published in 1614 the "Disquisitiones mathematicae" in Ingolstadt with Johann Georg Locher, in 1615 "Sol ellipticus" in Augsburg and with Georg Schönberger "Exegeses fundamentorum gnomonicorum" in Ingolstadt, and in 1617 he published "Refractiones coelestes", also in Ingolstadt. Scheiner took his remaining vows of poverty, chastity, obedience and loyalty before the Pope on 31 July 1617 in the town of Ingolstadt under Father Johannes Manhart S.J. In the very same year Scheiner made known his wish to go to China as a missionary. Father General Mutio Vitelleschi sent him a letter, however, telling Scheiner he had better stay in Europe and persevere with his mathematical studies. In the winter of 1617/1618, Scheiner returned to Innsbruck, Austria at the behest of Archduke Maximilian III.