Some excerpts from Mao's talks at the May 1942 Yenan Forum:
"To defeat the enemy we must rely primarily on the army with guns. But this army alone is not enough; we must also have a cultural army, which is absolutely indispensable for uniting our own ranks and defeating the enemy. ...
"In the last analysis, what is the source of all literature and art? Works of literature and art, as ideological forms, are products of the reflection in the human brain of the life of a given society. Revolutionary literature and art are the products of the reflection of the life of the people in the brains of revolutionary writers and artists. The life of the people is always a mine of the raw materials for literature and art, materials in their natural form, materials that are crude, but most vital, rich and fundamental; they make all literature and art seem pallid by comparison; they provide literature and art with an inexhaustible source, their only source. They are the only source, for there can be no other. ...
"Although man's social life is the only source of literature and art and is incomparably livelier and richer in content, the people are not satisfied with life alone and demand literature and art as well. Why? Because, while both are beautiful, life as reflected in works of literature and art can and ought to be on a higher plane, more intense, more concentrated, more typical, nearer the ideal, and therefore more universal than actual everyday life. Revolutionary literature and art should create a variety of characters out of real life and help the masses to propel history forward. For example, there is suffering from hunger, cold and oppression on the one hand, and exploitation and oppression of man by man on the other. These facts exist everywhere and people look upon them as commonplace. Writers and artists concentrate such everyday phenomena, typify the contradictions and struggles within them and produce works which awaken the masses, fire them with enthusiasm and impel them to unite and struggle to transform their environment. Without such literature and art, this task could not be fulfilled, or at least not so effectively and speedily. ...
"In the world today all culture, all literature and art belong to definite classes and are geared to definite political lines. There is in fact no such thing as art for art's sake, art that stands above classes or art that is detached from or independent of politics. Proletarian literature and art are part of the whole proletarian revolutionary cause; they are, as Lenin said, cogs and wheels in the whole revolutionary machine."
Read the whole here. I'll be posting more on how literature can serve the class struggle as soon as I can.