Medieval physicians would not operate on a part of the body while the Moon was in the sign that governed it. Aries the head, Taurus the throat, and so on down to Pisces at the feet.

The figure is called the zodiac man and appears in nearly every European physician's almanac for four hundred years. The rule was taken seriously enough that surgery was scheduled around it, and barber-surgeons carried a folding calendar to check. It survives almost unchanged in the American farming almanacs' advice on when to have teeth pulled.