Definition of mind
Mind, in Buddhism, refers to mental activity, not to a “thing” that is the agent of that activity or to a “tool” that a “me” uses to engage in that activity. The definition of mind describes the activity from two points of view. Thus, the two aspects of the description are simultaneous functions, not sequential: the mental activity of producing or giving rise (‘ char-ba) to cognitive appearances (snang-ba), the mental activity of cognitively engaging (‘ jug-pa) with cognitive appearances. The former is usually translated as clarity (gsal) and the latter as awareness (rig).
Cognitive appearances do not refer to appearances of things “out there,” which we may or may not notice and cognize. They refer to how things appear “to the mind” when we cognize them. In a sense, they are like mental holograms. For example, in nonconceptual sensory cognition such as seeing, colored shapes appear, which are merely mental representations (snang-ba, mental semblances) or mental derivatives (gzugs-brnyan, mental reflections) of one moment of colored shapes. In conceptual cognition, a mental representation appears of the conventional object, such as a hand, that the colored shapes in that moment are the visual sensibilia of. A sequence of mental representations of a hand each second one inch further to the right appears as motion. In other words, cognitive appearances exist only within the context of mental activity. They do not need to be clear or in focus.
Moreover, cognitive appearances do not refer merely to the images that appear “in the mind” when cognizing visible objects with our eyes. They also refer to the cognitive appearances or arisings (shar-ba) of sounds, smells, tastes, physical sensations, thoughts, emotions, and so on. After all, it is mental activity that makes a sequence of consonant and vowel sounds arise as words and sentences.
Note that the expressions “things appear to the mind” or “in the mind” are merely manners of speaking particular to the English idiom and reflect a dualistic concept of mind totally different from the Buddhist model.
Cognitively engaging with cognitive appearances may be in any manner, such as seeing, hearing, thinking, or feeling them, and does not need to be conscious or with understanding. It may include ignoring something and being confused about it.
The definition also adds the word mere (tsam), which implies that mental activity occurs without a concrete agent “me” making it happen. It also implies that fleeting stains are not the defining characteristic of this activity. The superficial (kun-rdzob, conventional) nature of mental activity is merely producing and engaging with cognitive appearances; its deepest (don-dam, ultimate) nature is its voidness.
Further, mental activity is individual and subjective. My seeing of a picture and my feeling of happiness are not yours. Moreover, Buddhism does not assert a universal mind that we all are part of, that we all can access, or that our mental continuums (mind-streams) merge with when we achieve liberation or enlightenment. Even when enlightened, each Buddha’s mental continuum retains its individuality.