Engels: Transition from Ape to Man

“Let us not flatter ourselves on account of our human victories over nature. For each such victory nature takes its revenge on us. Each victory, it is true, in the first place brings about the results we expected, but in the second and third places it has quite different, unforeseen effects which only too often cancel the first.”

- Engels - The Part Played by Labour in the Transition from Ape to Man, 1876

(Source: marxists.org)