"Why don't we just filter out the noise?" - asked the signal processing student to the teacher. "If we knew what was the noise and what was the signal we would

"Why don't we just filter out the noise?" - asked the signal processing student to the teacher. "If we knew what was the noise and what was the signal we wouldn't call it noise in the first place!" - and the student reflected silently. I predict most people will remove the wrong half of their docs if they follow this advice.