Java master Bawan said: “The beggar in the marketplace owns
nothing but empty cups. Fill all but one with tea and he
will praise you; yet spill a drop into the last and he must
instantly die of thirst. Explain.”
No monk could answer Bawan’s question. The teacher retired
to his chambers.
That evening four students came to his door, seeking help
with a truculent program. Its log files were overflowing
with ArrayIndexOutOfBounds exceptions which the students
insisted were impossible: the array in question was declared
to hold a thousand elements, and the index—a one-byte
integer—could never exceed 255 by definition.
Master Bawan pointed to an object in the corner. “What is
that?” he asked of each student.
“A broom,” said each in turn.
Bawan then grabbed the broom and swung it wide over the
heads of the students. Pictures were swept off the walls and
sent spinning to the floor. Vases and cups came crashing
down from their shelves. Paper screens tore. Dust fell from
the rafters.
“Not a broom!” shouted Master Bawan, still swinging like a
madman. “Not a broom!”
Qi’s Commentary
Each of the beggar’s cups is alike in every way to the one
beside it, yet each also holds twice as much as the cup to
its right. Now quickly say what it is.
Qi’s Poem
In the hand of a beggar, the staff engenders pity.
