Denis Waitley writes in "Your Absolute Bottom Line":

A true story: in the operating room of a large, well-known hospital, it was the surgical nurse's first day on the medical team, and she was responsible for ensuring that all instruments and materials were accounted for before completing the final steps of the operation. She said to the surgeon, "You've only removed 11 sponges. We used 12 sponges, and we need to find the last one."

"I removed them all," the doctor declared emphatically. "We'll close the incision now."

"No," the rookie nurse objected, "we used 12 sponges."

"I'll take the responsibility," the surgeon said grimly. "Suture."

"You can't do that, sir," blazed the nurse. "Think of the patient."

The surgeon smiled, lifted his foot and showed the nurse the 12th sponge.

"You'll do just fine in this or any other hospital."

When you know you're right, you can't back down.