...[T]he very existence of such powers argues a counterforce. We call powers of the first kind dark, though they may use a species of deadly light as Decuman did; and we call those of the second kind bright, though I think that they may at times employ darkness, as a good man nevertheless draws the curtains of his bed to sleep. Yet there is truth to the talk of darkness and light, because it shows plainly that one implies the other. The tale I read to little Severian said that the universe was but a long word of the Increate's. We, then, are the syllables of that word. But the speaking of any word is futile unless there are other words, words that are not spoken. If a beast has but one cry, the cry tells nothing; and even the wind has a multitude of voices, so that those who sit indoors may hear it and know if the weather is tumultuous or mild. The powers we call dark seem to me to be the words the Increate did not speak, if the Increate exists at all; and these words must be maintained in a quasi-existence, if the other word, the word spoken, is to be distinguished. What is not said can be important--but what is said is more important.
--The Sword of the Lictor, by Gene Wolfe, p 124-125.