The Mahaparinirvana-sutra says, 'All formations are impermanent; this is the law of appearing and disappearing. When appearing and disappearing disappear, then this stillness is bliss.' This means that when there is no appearance or disappearance in your mind, that mind is complete stillness and bliss. It is a mind utterly devoid of thinking. This is your mind before thinking. [...]
It is not possible to explain this point using words and speech.
Seung Sahn, The Compass of Zen, p. 231.