 Calvin developed his theology in his biblical commentaries as well as his sermons and treatises, but the most concise expression of his views is found in his magnum opus, the Institutes of the Christian Religion. He intended that the book be used as a summary of his views on Christian theology and that it be read in conjunction with his commentaries. The various editions of that work span nearly his entire career as a reformer, and the successive revisions of the book show that his theology changed very little from his youth to his death. The first edition from 1536 consisted of only six chapters. The second edition, published in 1539, was three times as long because he added chapters on subjects that appear in Melanchthon's Loci Communes. In 1543, he again added new material and expanded a chapter on the Apostles' Creed. The final edition of the Institutes appeared in 1559. By then, the work consisted of four books of eighty chapters, and each book was named after statements from the creed: Book 1 on God the Creator, Book 2 on the Redeemer in Christ, Book 3 on receiving the Grace of Christ through the Holy Spirit, and Book 4 on the Society of Christ or the Church.
