Study Hall - Shobogenzo

"Daowu, who would later become Zen master of the Tianhuang Monastery, visited the assembly of Shitou, Great Master Wuji, and asked, 'What is the fundamental meaning of buddha dharma?'
Shitou said, "Not to attain, not to know.'
Daowu said, 'Is there a further turning point in going beyond?'
Shitou said, 'The vast sky does not keep white clouds from flying.'...
Shitou said, Not to attain, not to know. Understand that in buddha dharma the fundamental meaning is in the original aspiration, as well as in the ultimate level. This fundamental meaning is not to attain. It is not that there is no aspiration, no practice, or no enlightenment. But simply, not-attaining. The fundamental meaning is not to know. Practice-enlightenment is not nonexistent or existent, but is not to know, not to attain." ('Going Beyond Buddha', 'Bukkojo Ji').