A Zen master's most famous question has no answer you can simply explain

In the 18th century, Japanese Zen master Hakuin Ekaku devised a new kind of koan for his students: 'You know the sound of two hands clapping — what is the sound of one hand?' Unlike a riddle with a clever solution, the koan is meant to exhaust ordinary logical thinking until insight breaks through some other way entirely.

— Hakuin Ekaku, The Essential Teachings of Zen Master Hakuin — c. 1753