Friedrich Engels

Just as Darwin discovered the law of development of organic nature, so Marx discovered the law of development of human history: the simple fact, hitherto concealed by an overgrowth of ideology, that mankind must first of all eat, drink, have shelter and clothing, before it can pursue politics, science, art, religion, etc.

I must be informed, that one of my great duties was, to obey the priests in all things; and this I soon learnt, to my utter astonishment and horror, was to live in the practice of criminal intercourse with them.