Tycho Brahe and AstrologyLike the fifteenth-century astronomer Regiomontanus, Tycho Brahe appears to have accepted astrological prognostications on the principle that the heavenly bodies undoubtedly influenced (yet did not determine) terrestrial events, but expressed scepticism about the multiplicity of interpretative schemes, and increasingly preferred to work on establishing a sound mathematical astronomy. Two early tracts, one entitled Against Astrologers for Astrology, and one on a new method of dividing the heavens into astrological houses, were never published and are now lost. Tycho also worked in the area of weather prediction, produced astrological interpretations of the supernova of 1572 and the comet of 1577, and furnished his patrons Frederick II and Rudolph II with nativities and other predictions. The horoscope shown here is the nativity of King Christian IV of Denmark, composed by Tycho a few weeks after his birth in 1577.
An astrological world-view was fundamental to Tycho's entire philosophy of nature. His interest in alchemy, particularly the medical alchemy associated with Paracelsus, was almost as long-standing as his study of astronomy, and Uraniborg was constructed as both observatory and laboratory. In an introductory oration to the course of lectures he gave in Copenhagen in 1574, Tycho defended astrology on the grounds of correspondences between the heavenly bodies, terrestrial substances (metals, stones etc.), and bodily organs. He was later to emphasise the importance of studying alchemy and astrology together with a pair of emblems bearing the mottoes Despiciendo suspicio - "By looking down I see upward" - and Suspiciendo despicio - "By looking up I see downward." As several scholars have now argued, Tycho's commitment to a relationship between macrocosm and microcosm even played a role in his rejection of Copernicanism and his construction of a third world-system.