The conjurer was arranging a new stage trick, and on the day before its introduction he asked his young son to help him.

“When I ask for a boy to come on the stage, you must come at once. But you must not do anything or say anything that will make the audience think that you know me.”

The boy said he understood everything and when the conjurer asked for help, he came forward quickly and was invited on the stage. When he got there, the conjurer said:

“Look at this boy! He has never seen me before, have you, my boy?”

“No, father!” answered the boy.