One day an extremely nervous dental patient came for a root-canal surgery. He was brought into the examining room and made comfortable in the reclining dental chair. The dentist then injected a numbing agent around the patient's tooth, and left the room for a few minutes while the medication took hold.

When the dentist returned, the patient was standing next to a tray of dental equipment, "What are you doing by the surgical instruments?" asked the surprised dentist.

Focused on his task, the patient replied, "I'm taking out the ones I don't like."