(Sometimes a second part is needed for clarification. )

The following morning,  the student took his accustomed seat a few paces from the wall facing the rising sun.  The master paced a circuit that kept him always equidistant from the student and the wall.

Before the sun stood overhead, the student finally achieved something akin to enlightenment. “Aha! ” he said. “Teacher I see now that you are diabolical. ”

Swiftly, the master administered a boot to the head, leaving the student a crumpled mess.

“You were almost right there.  But math is still hard, though not quite as hard as my boot.”