"Without concepts, leave your awareness, just as it is, in the steady vision of appearances. If you can do so, that is the best of meditations. In terms of recognizing the nature of awareness, the spiritual mentors of the past stated that it could be ascertained in the interval following the cessation of one thought and prior to the arising of the next thought. In that interval there is an emptiness. How long is this interval? It's a mistake to think it is short in duration. Rather, it is the very nature of both samsara and nirvana. In the very steady vision of appearances, right in the instant, in the instantaneous vision of the instantaneous moment of appearances, you can recognize the essential nature of the mind."
~Gyatrul Rinpoche's commentary on Union of Mahamudra and Atiyoga