Charlie: Now, we don't often think about it, but someone must have drawn this design, right?
Charlie: I want you to think of that artist... as a runner on the beach. He's leaving footprints, which record every decision he makes. Faster, slower, closer to the water, further away. Now these are counterfeit bills. A second artist trying to copy the original ... a second runner. Now, when that second runner tries to follow the exact same path as the first, it's impossible. Even if he's being careful, he can't match the footprints without leaving evidence of himself. Different foot different stride... that's how you spot a forgery.