This is one of three important treatises written by Luther in 1520 (The Babylonian Captivity of the Church and The Freedom of a Christian are the other two), following the Leipzig debate of 1519, his subsequent condemnation, and further pro-papal attacks on his position by Augustine von Aveld and Sylvester Prierias ("the Romanist at Leipzig"). In particular, Prierias' Epitome of a Reply to Martin Luther presented a strong statement of the pope's absolute power. Luther's treatise was in fact an open letter sent to his friend Nicholas von Amsdorf, but addressed to Emperor Charles V and the German nobility. The "nobility" is in many ways representative of the common people as a whole, the priesthood of believers as opposed to ecclesiastical kingship. The first part of the treatise attacks "three walls" of papal power; the second part consists of a list of various papal abuses; the third part outlines Proposals for Reform.