 Monotheism in Schmidt's view is the "natural" form of theism, which was later overlaid and "degraded" by polytheism after deceased ancestors' veneration became worship, and personified natural forces became worshipped as well as gods.Schmidt's hypothesis was controversially discussed during much of the first half of the 20th century.In the 1930s, Schmidt adduced evidence from Native American mythology, Australian aborigines and other primitive civilizations in support of his views.