87:4.5

When the doctrine of good and bad spirits finally matured, it became the most widespread and persistent of all religious beliefs. This dualism represented a great religio-philosophic advance because it enabled man to account for both good luck and bad luck while at the same time believing in supermortal beings who were to some extent consistent in their behavior. The spirits could be counted on to be either good or bad; they were not thought of as being completely temperamental as the early ghosts of the monospiritism of most primitive religions had been conceived to be. Man was at last able to conceive of supermortal forces that were consistent in behavior, and this was one of the most momentous discoveries of truth in the entire history of the evolution of religion and in the expansion of human philosophy.