Praxis

"The chief defect of all materialism up to now (including Feuerbach's) isthat objective reality, what we apprehend through our senses, is understoodonly in the form of the OBJECT of contemplation; but not as SENSUOUS HUMANACTIVITY, as practice; not subjectively. Hence, in opposition to materialism, the ACTIVE side was developed abstractly by idealism... Feuerbach wants sensuous objects really distinguished from objects of thought but he does not understand human activity itself is OBJECTIVE activity."
--Karl Marx