In 1520, Pope Leo X issued the papal bull Exsurge Domine, which condemned a position which Luther had maintained at the 1518 Heidelberg Disputation, namely that "After the Fall free will is something in name only and when it does what is in it, it sins mortally." Luther subsequently defended the proposition in his Defense and Explanation of All the Articles Unjustly Condemned by the Roman Bull of Leo X (1520), in the process stating that "free will is really a fiction...with no reality, because it is in no man's power to plan any evil or good. As the article of Wycliffe, condemned at Constance, correctly teaches: everything takes place by absolute necessity."