Philip Melanchthon (born Philip Schwartzerd) (1497-1560) was a German professor and theologian, a key leader of the Lutheran Reformation, and a friend and associate of Martin Luther. In the beginning of 1521 in his Didymi Faventini Versus Thomam Placentinum pro M. Luthero Oratio, he defended Luther by proving that Luther rejected only papal and ecclesiastical practises which were at variance with Scripture, but not true philosophy and true Christianity. The appearance of Melanchthon\'s Loci Communes Rerum Theologicarum seu Hypotyposes Theologicae (1521) was of great importance for the confirmation and expansion of the reformatory ideas. His most important theological work of this period was the Commentarii in Epistolam Pauli ad Romanos (1532). In ethics Melanchthon preserved and renewed the tradition of ancient morality and represented the Evangelical conception of life. His books bearing directly on morals were chiefly drawn from the classics, and were influenced not so much by Aristotle as by Cicero. His principal works in this line were Prolegomena to Cicero\'s De Officiis (1525); Enarrationes Librorum Ethicorum Aristotelis (1529); Epitome Philosophiae Moralis (1538); and Ethicae Doctrinae Elementa (1550).