The relationship between the German Reformers Martin Luther and Philip Melanchthon has been puzzled over by scholars for centuries. They were fellow professors at the University of Wittenberg and collaborated on a number of projects, from a German translation of the Bible to the Augsburg Confession. Yet, there were undoubtedly some theological differences between them in later years, and all their contemporaries noted that their personalities were essentially opposites. Luther himself once characterized the relationship in the following way.
I am rough, boisterous, stormy, and altogether warlike. I am born to fight against innumerable monsters and devils. I must remove stumps and stones, cut away thistles, and thorns, and clear the wild forests; but Master Philip comes along softly and gently, sowing and watering with joy, according to the gifts which God has abundantly bestowed upon him.