Perception can be categorized into three levels: experience, emptiness, and luminosity. [Editor's note: We discussed the first two in previous quotes.] The third level of perception is luminosity. This has nothing to do with any visually bright light, but it is a sense of sharp boundary and clarity that does not have a theoretical or intellectualized reference point. It is realized on the spot, within the spaciousness of experience. If there were no space, experience would be unfocused; there would be no sharpness. In terms of our ordinary experience, luminosity is that we have a sense of clarity and a sense of things as they are, seen as they are, unmistakably.
From "Nobody's World," in True Perception: The Path of Dharma Art, page 106.