There is in fact no such thing as art for art's sake, art that stands above classes, art that is detached from or independent of politics. Proletarian literature and art are part of the whole proletarian revolutionary cause.
There is nothing more becoming a wise man than to make choice of friends, for by them thou shalt be judged what thou art. Let them therefore be wise and virtuous, and none of those that follow thee for gain; but make election rather of thy betters than thy inferiors; shunning always such as are poor and needy, for if thou givest twenty gifts and refuse to do the like but once, all that thou hast done will be lost, and such men will become thy mortal enemies.
There is only one art, whose sole criterion is the power, the authenticity, the revelatory insight, the courage and suggestiveness with which it seeks its truth. Thus, from the standpoint of the work and its worth it is irrelevant to which political ideas the artist as a citizen claims allegiance, which ideas he would like to serve with his work or whether he holds any such ideas at all.
Those only are happy who have their minds fixed on some object other than their own happiness: on the happiness of others, on the improvement of mankind, even on some art or pursuit followed not as a means, but as itself an ideal end. Aiming at something else, they find happiness by the way.