The Fourth Letter deals with the question of "actual grace", the Jesuits claiming that sin could only be committed if people had knowledge of the evil inherent to the planned action. The Jesuit priest with whom Pascal was speaking quoted Le Moyne, a professor to the Sorbonne from 1642 to 1654. Le Moyne's definition had already been used by Arnauld in the "Apologie pour les saints Pères":1. On the one hand, God sheds abroad on the soul some measure of love, which gives it a bias toward the thing commanded; and on the other, a rebellious concupiscence solicits it in the opposite direction. 2. God inspires the soul with a knowledge of its own weakness. 3. God reveals the knowledge of the physician who can heal it. 4. God inspires it with a desire to be healed. 5. God inspires a desire to pray and solicit his assistance.“And unless all these things occur and pass through the soul,” added the Jesuit, “the action is not properly a sin, and cannot be imputed, as M. le Moine shows in the same place and in what follows."