The Ninety-five Theses or Disputation on the Power of Indulgences are a list of propositions for an academic disputation written in 1517 by Martin Luther, professor of moral theology at the University of Wittenberg, Germany, that started the Reformation, a schism in the Catholic Church which profoundly changed Europe. They advance Luther's positions against what he saw as abusive in the practice of clergy selling plenary indulgences, which were certificates believed to reduce the temporal punishment for sins committed by the purchasers or their loved ones in purgatory.