"Auden wrote that 'art is a product of history, not a cause': 'it does not re-enter history as an effective agent'. Though this formulation is preferable to 'Poetry makes nothing happen', I would phrase it differently. A poem re-enters history in a multitude of circumstances, and it may indeed do so as an effective agent, or hostage. Nonetheless, whatever historical effects it may produce, or be made to produce, are as collusive with good and ill or as absurd as those of any other historical entity. Yet the poem - the true poem, the poem that has got within its judgement the condition of its judgement - is not exhausted by the uses to which it is put; it is alienated from its existence as historical event. This intolerable condition, rejected, may lead a poet to a political aesthetics; embraced, to an apolitical one; these twin betrayals - Yeats's 'Three Songs to the One Burden' on the one hand and his 'On being asked for a War Poem' or the late 'Politics' on the other - haunt modernist poetics."
Geoffrey Hill, "A Postscript on Modernist Poetics"