Medical astrology. 17th-century artwork of the human condition as a microcosm of day and night. This artwork was published in 1617, and shows the ideas of the English astrologer and mystic Robert Fludd (1574-1637). It shows how physicians thought the universe (the Macrocosm) was reflected in the human body (the Microcosm), a central concept in the astrology and natural philosophy of medieval Europe and the Renaissance. Fludd tried to explain the circulation of the blood using this microcosm theory, but failed. Here, the human body centres on the Earth, around which are spheres marking the path of the Sun (corresponding to the heart), and beyond that the spheres of the sky. The diagram is also divided into day (upper half) and night (lower half).