My cheek puff sign: Bell's palsy, Charles Bell and Dr Robert Knox.

Bell's palsy fully recovers in the great majority of cases. What may not be sufficiently appreciated is how distressing it can be. This Perspective recounts a personal experience; describes an unrecorded puzzling physical sign; and details the interest the experience generated in Charles Bell and in the infamous Robert Knox, whose paths crossed. Both deserve to be better known than just for a palsy or a murder-for-bodies scandal. Bell made a seminal contribution to neurophysiology, regarded by some as important as Harvey's discovery of the circulation of the blood. He was also a very accomplished artist, his paintings of wounded soldiers in the Napoleonic Wars among the best-ever artistic depictions of the mutilations of war. Knox published seven books and over 100 scientific papers and is a more multidimensional and interesting character than popularly portrayed.