Girolamo Cardano, Libelli quinque, Nuremberg: J. Petreius, 1547, 178 recto, leaf height 23 cm, N.3.13.

Astrology was part of the worldview of sixteenth-century physicians. They believed, for example, that the position and phase of the Moon affected the amount and place from which blood could be let. Genitures (charts indicating the planetary positions at the time of conception or birth) were regarded as indicating individual character traits; traditionally, astrology was defended against determinism with the idea that the stars ‘inclined’, but did not determine an individual’s fate. In this sense, an astrological chart may be regarded as a portrait of a person.

Girolamo Cardano (1501-1576) a Milanese physician, mathematician, and astrologer, was a prolific author. This book contained 100 examples of horoscopes of famous people Cardano had cast, in order to demonstrate his expertise and connections with the elite. This page shows Vesalius’s birth horoscope calculated for 30 December 1514, 5:45 pm. The relative positions of various planets (called aspects), as mapped out in the chart explain Vesalius’s distinctions. As Cardano describes, the quadrate aspect of Mars and the Moon means Vesalius excels in diligence and manual dexterity; Mercury’s aspects with Jupiter and Venus signify amazing talent (ingenium) and flair for the demands of his art. The Moon opposite the Sun indicates he has memory and knowledge, as well as many enemies. Saturn’s position and aspect with Mercury means profound talent, memory and diligence. Other planetary positions further signify glory from his art and favour from princes. Cardano described Vesalius as famous in life and predicted that he would also be famous after death. At the time this was written, Vesalius had become physician to Emperor Charles V, so Cardano’s prediction was a form of flattery; yet Vesalius’s fame did endure.