A metaphor is semantic. A double negative, on the other hand, is syntactical: two negations in their right places in a sentence usually lead to an affirmation (in the wrong places, they could be merely an intensified negation). A double negative, in the sense of two wrongs making a right, is a form of strategic long-windedness. To use two terms of negation, to say, for instance, that something is “not unlike” something else, is not the same as to say it is like that thing. Double negatives register instances of self-canceling misdirection. They are about doubt, the productive and counterproductive aspects of doubt, the pitching ground, the listing figure, and the little gap between intention and effect.

— Teju Cole, Known and Strange Things, 2016, Random House