Apophasis · the way of unsaying

A discipline, not a modesty: say what the source is not, strip every predicate including the good ones, and then strip the stripping. What is left is called darkness, and the darkness is described as an excess of light rather than an absence of it.

The technique behind "of Ein Sof nothing may be said." Plato's 509b starts it, Plotinus makes it a habit, Dionysius makes it a method, and the Kabbalah receives it as a rule of speech.