 In the medieval period, Peter Abelard argued that God must create the best of all possible worlds. If he didn’t, Abelard argues, there would have to be some reason for it. But what reason could that be except God’s injustice or jealousy? But God cannot be unjust or jealous. So there is no possible reason for God making anything less than the best. Everything has a reason. Thus God makes the best possible world (McCallum 1948, 93). Abelard’s opinion was rejected as heresy and mainstream opinion of philosophers during the Middle Ages appears to reject the PSR. God, on the mainstream medieval view, enjoys freedom of indifference with respect to his creation. Thus there is no sufficient reason for why God created what he did and the PSR slips from prominence until its early modern revival at the hands of Spinoza and Leibniz.