At all events, the materialist outlook on nature means nothing more than the simple conception of nature just as it is, without alien addition… (Engels, Dialectics of Nature, History of Science, omitted from Feuerbach.)
Dialectics, on the other hand [as opposed to metaphysics], comprehends things and their representations, ideas, in their essential connection, concatenation, motion, origin, and ending. (Engels, Anti-Dühring, Introduction, General.)