" What worried Dave,” Bryant continued, “is this appearance of the new Nexus-6 advanced type. The Rosen organization assured us, as you know, that a Nexus-6 could be delineated by standard profile tests. We took their word for it. Now we’re forced, as we knew we would be, to determine it on our own. That’s what you’ll be doing in Seattle. You understand, don’t you, that this could go wrong either way. If you can’t pick out all the humanoid robots, then we have no reliable analytical tool and we’ll never find the ones who’re already escaping. If your scale factors out a human subject, identifies him as android— "

― Philip K. Dick , Do Androids Dream of Electric Sheep?