  In On the Fall of the Devil (De casu diaboli) Anselm extends his account of freedom and sin by discussing the first sin of the angels. In order for the angels to have the power to preserve rectitude of will for its own sake, they had to have both a will for justice and a will for happiness. If God had given them only a will for happiness, they would have been necessitated to will whatever they thought would make them happy. Their willing of happiness would have had its ultimate origin in God and not in the angels themselves. So they would not have had the power for self-initiated action, which means that they would not have had free choice. The same thing would have been true, mutatis mutandis, if God had given them only the will for justice.