As hitherto he had simply graduated as a master in philosophy, and had not qualified himself academically for a professor of theology, Luther at first was only called on to lecture on those philosophical subjects which, as we have seen, occupied his studies at Erfurt. Theologians, it is true, had been entrusted with these duties, just as, here at Wittenberg, the first dean of the philosophical faculty was a theologian, and, in addition to that indeed, a member of the Augustinian Order. But from the beginning, Luther was anxious to exchange the province of philosophy for that of theology, meaning thereby, as he expressed it, that theology which searched into the very kernel of the nut, the heart of the wheat, the marrow of the bones. So far, he was already confident of having found a sure ground for his Christian faith, as well as for his inner life, and having found it, of being able to begin teaching others. Indeed, while busily engaged in his first lectures on philosophy, he was preparing to qualify himself for his theological degrees. Here also he had to begin with his baccalaureate, comprising in fact three different steps in the theological faculty, each of which had to be reached by an examination and disputation. The first step was that of bachelor of biblical knowledge, which qualified him to lecture on the Holy Scriptures. The second, or that of a _Sententiarius_, was necessary for lecturing on the chief compendium of mediaeval School-theology, the so-called Sentences of Peter Lombardus, the due performance of which duly led to the attainment of the third step. Above the baccalaureate, with its three grades, came the rank of licentiate, which gave the right to teach the whole of theology, and lastly the formal, solemn admission as doctor of theology. Already, on March 9, 1509, Luther had attained his first step in the baccalaureate. At the end of six months he was qualified, by the statutes of the university, to reach the second step, and in the course of the next six months he actually reached it. But before gaining his new rights as a _Sententiarius_, he was summoned back by the authorities of his Order to Erfurt. The reason we do not know; we only know that he entered the theological faculty there as professor, receiving, at the same time, the recognition of the academical rank he had acquired at Wittenberg. At Erfurt he remained about three terms, or eighteen months. After that he returned to the university at Wittenberg. Trutvetter, towards the end of 1510, had received a summons back to Erfurt from Wittenberg. The void thus caused by his summons away may have had something to do with Luther's return thither. At all events his position at Wittenberg was now vastly different from that which he had previously held. No theologian, his superior in years or fame, was any longer above him.