Diagnosis before prescription

This makes my friends and I laugh every time we read it. It's taken from my health science readings. But as funny as it is, it does teach a very important lesson of how you shouldn't never diagnose before you prescribe.

Suppose you've been having trouble with your eyes and you decide to go to an optometrist for help. after briefly listening to your complaint, he takes off his glasses and hands them to you.

"Put these on," he says. "I've worn this pair of glasses for ten years now and they've really helped me. I have an extra pair at home; you can wear these."

So you put them on, but it only makes the problem worse.

"This is terrible!" you exclaim. "I can't see a thing!"

"Well, what's wrong?" he asks. "They work great for me. Try harder."

"I am trying," you insist. "Everything is a blur."

"Well, what's the matter with you? Think positively."

"Okay. I positively can't see a thing."

"Boy, are you ungrateful!" he chides. "And after all I've done to help you!"