Neoplatonism Through the Renaissance
How did Peter Lombard answer his question of whether God was the cause of evil and sin?
God is of course good and has a good nature. Out of this good nature, God created an angel. This angel became evil after God created him and passed his evil on to man. Evil in man resulted in sin. God was therefore not the first cause of either human evil or sin. (Lombard’s explanation is similar to how we would explain how a good parent has a bad child—at some point the creation or offspring is morally responsible for itself and Lombard located that point originally in an angel.)
Lombard (c. 1095–1160) wrote about this and other issues in his four-volume Book of Sentences (1145–1151) that soon became a standard text for theological training that was in use until the mid 1200s. Others would begin with his work and then develop their own ideas on its basis.