Marx, Karl. Theses on Feuerbach. Marxists.org.

Excerpt:

“The main defect of all hitherto-existing materialism — that of Feuerbach included — is that the Object [der Gegenstand], actuality, sensuousness, are conceived only in the form of the object[Objekts], or of contemplation [Anschauung], but not as human sensuous activity, practice [Praxis], not subjectively. Hence it happened that the active side, in opposition to materialism, was developed by idealism — but only abstractly, since, of course, idealism does not know real, sensuous activity as such. Feuerbach wants sensuous objects [Objekte], differentiated from thought-objects, but he does not conceive human activity itself as objective [gegenständliche] activity. In The Essence of Christianity [Das Wesen des Christenthums], he therefore regards the theoretical attitude as the only genuinely human attitude, while practice is conceived and defined only in its dirty-Jewish form of appearance [Erscheinungsform]^[1]. Hence he does not grasp the significance of ‘revolutionary’, of ‘practical-critical’, activity.”

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