to live with his maternal grandmother, Elizabeth Reuter, sister of Reuchlin. The next year he entered the University of Heidelberg, where he studied philosophy, rhetoric, and astronomy/astrology, and became known as a scholar of Greek. Denied the master's degree in 1512 on the grounds of his youth, he went to Tübingen, where he continued humanistic studies but also worked on jurisprudence, mathematics, and medicine. While there he was also taught the technical aspects of astrology by Johannes Stöffler. After gaining a master's degree in 1516, he began to study theology. Under the influence of Reuchlin, Erasmus, and others, he became convinced that true Christianity was something different from the scholastic theology as taught at the university. He became a conventor (repentant) in the contubernium and instructed younger scholars. He also lectured on oratory, on Virgil and on Livy. His first publications were a number of poems in a collection edited by Jakob Wimpfeling (), the preface to Reuchlin's Epistolae clarorum virorum (1514), an edition of Terence (1516), and a Greek grammar (1518). Professor at Wittenberg Opposed as a reformer at Tübingen, he accepted a call to the University of Wittenberg from Martin Luther on the recommendation of his great-uncle, and became professor of Greek there at the age of 21. He studied the Scriptures, especially of Paul, and Evangelical doctrine. Attending the disputation of Leipzig (1519) as a spectator, he nonetheless participated with his comments. After his views were attacked by Johann Eck, Melanchthon replied based on the authority of Scripture in his Defensio contra Johannem Eckium (Wittenberg, 1519). Following lectures on the Gospel of Matthew and the Epistle to the Romans, together with his investigations into Pauline doctrine, he was granted the degree of bachelor of theology, and transferred to the theological faculty. He married Katharina Krapp (Katharina article from the German Wikipedia), (1497–1557) daughter of Wittenberg's mayor, on 25 November 1520. They had four children: Anna (Anna article from the German Wikipedia), Philipp, Georg, and Magdalen. Theological disputes In the beginning of 1521, Melanchthon defended Luther in his Didymi Faventini versus Thomam Placentinum pro M. Luthero oratio (Wittenberg, n.d.). He argued that Luther rejected only papal and ecclesiastical practises which were at variance with Scripture. But while Luther was absent at Wartburg Castle, during the disturbances caused by the Zwickau prophets, Melanchthon wavered. The appearance of Melanchthon's Loci communes rerum theologicarum seu hypotyposes theologicae (Wittenberg and Basel, 1521)