What is the Sound of a Single Hand?
When you clap together both hands a sharp sound is heard; when you raise the one hand there is neither sound nor smell…
If conceptions and discriminations are not mixed within it and it is quite apart from seeing, hearing, perceiving, and knowing, and if while walking, standing, sitting, and reclining, you proceed straightforwardly without interruption in the study of this koan, then in the place where reason is exhausted and words are ended, you will suddenly pluck out the karmic root of birth and death and break down the cave of ignorance.
Hakuin’s own explanation, as translated by Phillip Yampolksy in The Zen Master Hakuin: Selected Writings, pg. 164
RP I particularly like the phrase ‘breakdown of the cave of ignorance’. Of course we are inevitably reminded of Plato’s allegory of the Cave – https://en.wikipedia.org/wiki/Allegory_of_the_Cave
I recall that in one of his early books Guy Claxton refers to a Zen teacher who asked why Westerners go East in their spiritual search when what is to be found lies in our ancient teachers, such as Plato.
Of course it is delicious and delightful to juxtapose teachings from East and West!