An old man went to his doctor because his leg was bothering him. He was in terrible pain.
The doctor said “I am afraid it’s just old age. There is nothing we can do about it.”
The old man was beside himself. “That can’t be! You don’t know what you’re talking about!
The doctor got mad and raised his voice to the old man and said “How can you say that to me? You’re telling me I’m wrong?!”
“Obviously you are wrong!” the old man replied. “My other leg is fine, and it’s the exact same age!”