An old man witnesses a burglary and appears in court.
The defense lawyer asks him, "Did you see my client commit this burglary?"
"Yes," the man says. "I saw him plainly take the goods."
The lawyer adds, "This happened at night. Are you sure you saw my client commit this crime?"
"Yes, I saw him do it," the man says.
The lawyer says, "You are 80 years old and your eyesight probably is bad. Just how far can you see at night?"
The man says, "I can see the moon. How far is that?"