Date: August 6 and 20, 1859

"The jaded cart-horse of the commonplace bourgeois mind falters of course in confusion in front of the ditch separating substance from appearance, and cause from effect; but one should not ride carthorses if one intends to go coursing over the very rough ground of abstract reasoning."

— Engels, Friedrich (1820-1895)

Date: 1964

"Its productivity and efficiency, its capacity to increase and spread comforts, to turn waste into need, and destruction into construction, the extent to which this civilization transforms the object world into an extension of man's mind and body makes the very notion of alienation questionable. ...

— Marcuse, Herbert (1898-1979)