What could be more unpredictable than our thoughts and emotions: do you have any idea what you are going to think or feel next? Our mind, in fact, is as empty, as impermanent, and as transient as a dream. Look at a thought: It comes, it stays, and it goes. The past is past, the future not yet risen, and even the present thought, as we experience it, becomes the past.

The only thing we really have is nowness, is now.

Sogyal Rinpoche, The Tibetan Book of Living and Dying