“A young martial artist is seeking to study with a sage. As the sage explains facets of his training and philosophy, the student frequently interrupts with “Oh, yes, I know that.” At one point, the sage is pouring the student tea, and keeps pouring until the cup generously overflows. The student jumps up before the tea scalds him, and demands to know “How can such a great master spill tea like that?” The sage stops pouring and replies, “If you wish to sample my tea, you must first empty your cup.”
The Parable of the Empty Cup. The Shaolin Grandmasters’ Text, 2006 by Order Of Shaolin Ch’an, p. 76.