Here, however, he could not stop. The desire of his heart must be accomplished. The same power which formerly pushed him from the bar into the monastic life now pushed him from philosophy towards the Bible. He zealously commenced the study of ancient languages, especially Greek and Hebrew, that he might be able to draw science and learning at the fountain-head. He was all his life an indefatigable student.[191] Some months after his arrival at the university he applied for the degree of Bachelor in Divinity, and obtained it in the end of March 1509, with a special injunction to devote himself to biblical theology, _ad Biblia_. [191] "In studiis literarum, corpore ac mente indefessus." (Pallavicini, Hist. Conc. Trid. i, 16.) In literary pursuits, he was indefatigable in mind and body. Every day at one, Luther had to lecture on the Bible,--a precious employment both for the professor and his pupils--giving them a better insight into the divine meaning of those oracles which had so long been lost both to the people and the school. He began his lectures with an exposition of the Psalms, and shortly after proceeded to the Epistle to the Romans. It was especially when meditating upon it that the light of truth entered his heart. After retiring to his quiet cell he spent hours in the study of the Divine Word--the Epistle of St. Paul lying open before him. One day, coming to the seventeenth verse of the first chapter, he read these words of the prophet Habakkuk, "_The just shall live by faith_." He is struck with the expression. The just, then, has a different life from other men, and this life is given by faith. These words, which he receives into his heart as if God himself had there deposited them, unveils the mystery of the Christian life to him, and gives him an increase of this life. Long after, in the midst of his numerous labours, he thought he still heard a voice saying to him, "The just shall live by faith."[192] [192] Seckend., p. 55. Luther's lectures, thus prepared, had little resemblance to those which had hitherto been delivered. It was not a declamatory rhetorician, or a pedantic schoolman that spoke; it was a Christian who had felt the power of revealed truth--truth which he derived from the Bible, and presented to his astonished hearers, all full of life, as it came from the treasury of his heart. It was not a lesson from man, but a lesson from God.