A central question of the sociology of religion is the source of religious beliefs. Two classic statements are as follows: From Engel's Anti-Duhring:All religion, however, is nothing but the phantastic reflection in men's minds of those external forces which control their daily life, a reflection in which the terrestial forces assume the form of supernatural forces… But it is not long before, side by side with the forces of Nature, social forces begin to be active; forces which present themselves to man as equally extraneous and at first equally inexplicable, dominating them with the same apparent necessity, as the forces of Nature themselves… We have already seen, more than once, that in existing bourgeoise society men are dominated by the economic conditions created by themselves, by the means of production which they themselves have produced, as if by an extraneous force. The actual basis of religious reflex action therefore continues to exist, and with it the religious reflex itself. (Engels 1966, 344–345)