From the Middle Ages to the Enlightenment, bodily fluids or "humors" - whether blood, semen, or phlegm - obsessed the educated and ignorant alike. These "elixirs" were believed to possess magical powers guaranteeing long life, sexual potency, intellectual insight (particularly in women), and even holiness.

Piero Camporesi, a specialist in popular culture from the Middle Ages to the Enlightenment, tells this fascinating story with an abundance of examples, still of great relevance to those of us who drink "cordials" for revitalizing the heart, take potions for sexual vigor, and believe that a ruddy complexion is a sign of health.

This is also a proto-feminist story, for women's purified body, with its menstrual discharge, endows her with greater intelligence - a paradoxical but revolutionary conclusion in an era of misogyny.