The medical student was shocked when he received a failing grade in radiology.

Approaching the professor, he demanded to know the reason for the grade.

"You know the self X-ray you took?" asked the professor.

"I do," recalled the student.

"A fine picture," the professor said, "of your lungs, stomach and liver."

"If it's a fine picture, then why did you give me an F?"

"I had no choice," said the professor. "You didn't put your heart into it."