During a visit to a mental asylum, a visitor asked the director, "What is the criterion for deciding whether a patient should be institutionalized?"
"Well," said the director, "we fill a bathtub with water, then give the patient a teaspoon, a teacup, and a bucket. We ask him to empty the bathtub."
"Oh, I understand," said the visitor. "A normal person would choose the bucket because it's larger than the spoon or the cup."
"No!" answered the director. "A normal person would pull the plug."