Here's a somewhat romanticized vision what a code review is:
What am I going to do? I get an idea. Maybe it's a valve. I take my finger and put it down on one of the mysterious little crosses in the middle of one of the blueprints on page three, and I say, ``What happens if this valve gets stuck?'' --figuring they're going to say, ``That's not a valve, sir, that's a window.''
So one looks at the other and says, ``Well, if that valve gets stuck--'' and he goes up and down on the blueprint, up and down, the other guy goes up and down, back and forth, back and forth, and then both look at each other. They turn around to me and they open their mouths like astonished fish and say, ``You're absolutely right, sir.''
Quoted from "Surely You Are Joking, Mr. Feynman!".