From The Redress of Poetry by Seamus Heaney.
And the project of the [Christopher Marlowe] plays can be represented to some extent by an analogy first proposed by the South African writer Andre Brink in relation to the role of writers in a repressed society. People in such societies, according to Brink, typically employ only a portion of the alphabet that is available to them as human beings. In matters of race or sex or religion, citizens will confine the range of their discourse to a band of allowable usages, say, A and M. This will be a more or less conscious act of self-censorship, as much a collusion as a consensus. So it then becomes the writer’s task to expose this state of affairs, to extend the resources of expression up to perhaps N or V, and thereby both to affront and enlighten.