Even for the wink of an eye or a flash of lightning, nothing lasts

“When engaged in noticing continuously both the dissolution of objects and the act of knowing, he (the meditator) reflects: ‘Even for the wink of an eye or a flash of lightning, nothing lasts. One did not realize this before. As things ceased and vanished in the past, so will they cease and vanish in the future.’ One must notice such a reflection.”

~ from the book, Practical Insight Meditation