Anthroposophic medicine departs from fundamental biological principles in several respects. For example, Steiner said that the heart does not pump blood but that blood propels itself along. Anthroposophic medicine also proposes that patients' past lives may influence their illness and that the course of an illness is subject to karmic destiny. Professor of complementary medicine Edzard Ernst and other physicians and scientists including Simon Singh and David Gorski have characterized anthroposophic medicine as pseudoscientific quackery with no basis in reason or logic.