“The past mind has ceased and disappeared. The future mind has not arisen or appeared. The present mind is very hard to examine. If you analyze and investigate what can be shown through reasonings—that the present mind has no color or shape; that, like space, it does not exist; that it is neither singular nor a plurality; that it does not arise; or that it is naturally luminous—you will realize it does not exist.
If both material and nonmaterial entities are things that have no essence at all and are simply nonexistent, discerning prajñā also does not exist. An analogy is fire: the fire that arises from rubbing two sticks together will burn up the sticks and, when they no longer exist, the fire that consumed them will go out on its own.
Similarly, when prajñā has proven that all phenomena—both specifically characterized and generally characterized—do not exist, that prajñā disappears and is luminosity, which has no essence at all. Thus, everything that could be a flaw (such as dullness or agitation) is cleared away.
At this point, mind does not think about anything, it does not grasp at anything. Mindfulness and attentiveness are cast aside. As long as the enemy, or thief, of characterizing or conceptualizing does not arise, rest mind that way.“
—Atiśa Dīpaṃkara Śrījñāna (982–1055), Madhyamakopadeśa