It is the work LOCI COMMUNES, _the principal articles of Christian doctrine_, as they were afterwards called. We have already heard that Melanchthon devoted himself especially to the writings of Paul. He gathered together all the principal truths of this apostle, and presented them to his hearers. These were so highly pleased with the production, that they had it published. As Melanchthon, however, discovered many imperfections in it, he published it himself in 1521, corrected and enlarged. This volume, which may be called the first system of religion in the evangelical church, was everywhere greeted in the most friendly manner. Luther was quite delighted with it, and once said of it, that it was not only worthy of immortality, but even to be admitted into the canon of Scripture. In his table-talk he expressed the following opinion of it: "Whoever wishes to become a theologian now, enjoys great advantages; for first of all, he has the Bible, which is so clear, that he can read it without difficulty. Then let him read in addition the Loci Communes Philippi; let him read them diligently and well, that he may impress them upon his mind. If he has these two things, he is a theologian, from whom neither the devil nor heretics shall be able to take away anything. To him the whole field of theology lies open, so that he is able to read anything he pleases after that with edification."
Melanchthon issued improved editions of the work from time to time. Seldom has a book met with so extensive a demand. We can form an estimate of its value from this fact alone. But it was also totally different from the old trash which Melanchthon had become acquainted with in Tübingen. It followed the pure dictates of the Bible, and was thoroughly practical. Here the doctrines of sin, of the law and the Gospel, of Justification, of Faith and Good Works, were developed in a convincing manner, as they had been brought to light after a long midnight, by Luther himself. With this work he stood entirely upon the Bible, and on this account it was so refreshing to friends and annoying to enemies. In September, 1519, he was made a Bachelor of Divinity on account of his great learning. He would never accept a higher degree, and always remained a Magister (Master.) But Luther said of him: "It is true he is but a poor Master, but also a Doctor above all Doctors."