Darkness cannot say: “I precede the coming light”, but there is a sense in which light can say, “Darkness preceded me”.
Doubtless there is an event, X, in the future, by reference to which we may say that we are at present in a category of Not-X, but until X occurs, the category of Not-X is without reality. Only X can give reality to Not-X; that is to say, Not-Being depends for its reality upon Being. In this way we may faintly see how the creation of Time may be said automatically to create a time when Time was not, and how the Being of God can be said to create a Not-Being that is not God.
Everything written symbols can say has already passed by. They are like tracks left by animals. That is why the masters of meditation refuse to accept that writings are final. The aim is to reach true being by means of those tracks, those letters, those signs - but reality itself is not a sign, and it leaves no tracks. It doesn’t come to us by way of letters or words. We can go toward it, by following those words and letters back to what they came from. But so long as we are preoccupied with symbols, theories and opinions, we will fail to reach the principle.
"But when we give up symbols and opinions, aren’t we left in the utter nothingness of being?"
Perceptual: "They couldn't figure out what to do next", "they couldn't find the feature", "they didn't know they could click that button..." etc.
Domain-specific: "We need a way to jump back here because in their workflow this happens..."
In general, usability testing only catches type 1 perceptual problems. Because in those tests you take people out of the real world and assign them tasks. Usability testing doesn't catch domain-specific problems because they only come up in real life use.