I came across this lovely story while doing research for my book.
There was a Japanese Zen master named Nan-in who lived during the Meiji era (1868-1912). Once, a university professor came to visit him to learn about Zen. When the master had spoken for a while the professor interrupted and said ‘Oh I already know that’, in an attempt to impress the Master. The Master then invited him to discuss the matter over tea. The Master quietly prepared and poured the tea. When the tea was filled to the cup’s brim, he kept pouring. The professor watched the overflowing cup until he could no longer restrain himself. “It’s full! No more will go in!” blurted the student. “Exactly, said the Master. Return to me when your cup is empty.”
