TERRY EAGLETON ON THOUGHT

From Why Marx Was Right (2011):

Our thought is bound up with the world in another sense, too.  It is not just a "reflection" of reality, but a material force in its own right.  Marxist theory itself is not just a commentary on the world, but an instrument for changing it.  Marx himself occasionally talks as though thought were a mere "reflex" of material situations, but this fails to do justice to his own more subtle insights.  Certain kinds of theory--emancipatory theories, as they are generally known--can act as a political force within the world, not just as a way of interpreting it.  And this lends them a peculiar sort of feature.  It means that they form a link between how things are and how they might be.  They provide descriptions of how the world is; but in doing so they can help change the way men and women understand it, which in turn can play a part in changing reality.  (emphasis added)