In the ordinary mind, we perceive the stream of thoughts as continuous, but in reality this is not the case. You will discover for yourself that there is a gap between each thought. When the past thought is past, and the future thought has not yet arisen, you will always find a gap in which the Rigpa, the nature of mind, is revealed. So the work of meditation is to allow thoughts to slow down, to make that gap become more and more apparent.
Sogyal Rinpoche - Tibetan Book of Living and Dying