Here I’d been describing grammar as train tracks for the brain — brain tracks — and accordingly, describing what happens in the case of bad grammar, particularly grammatical ambiguity (where you come to a fork in the track or stray down the blind spur of a misreading), as a derailing.
How 19th century of me! Obviously, it’s time I got with the program. The grammar part of your brain is a GPS, and a bad writer is a bad driver. When he or she gets you lost, you can just hear your brain draw itself up and say in that icy, nasal voice, dripping with contempt and barely controlled patience, “RECALCULATING.”