Engels : paraphrases Marx’s famous quote on Being determining Consciousness; Notice to determine something is to change it; Does it require deep intuition to comprehend that man’s (sic) ideas, views, and conception, in one word, man’s consciousness, _changes_ ( emphases added - CB)with every _change_ in the conditions of his material existence, in his social relations and in his social life? What else does the history of ideas prove, than that intellectual production _changes_ its character in proportion as material production is changed? The ruling ideas of each age have ever been the ideas of its ruling class. When people speak of the ideas that revolutionise society, they do but express that fact that within the old society the elements of a new one have been created, and that the dissolution (change) of the old ideas keeps even pace with the dissolution ( change) of the old conditions of existence."

Engels : "Does it require deep intuition to comprehend that man’s (sic) ideas, views, and conception, in one word, man’s consciousness, _changes_ ( emphases added - CB)with every _change_ in the conditions of his material existence, in his social relations and in his social life? What else does the history of ideas prove, than that intellectual production _changes_ its character in proportion as material production is changed? The ruling ideas of each age have ever been the ideas of its ruling class. When people speak of the ideas that revolutionise society, they do but express that fact that within the old society the elements of a new one have been created, and that the dissolution (change) of the old ideas keeps even pace with the dissolution ( change) of the old conditions of existence."