an English soldier, Member of Parliament, and writer on astrology. Heydon was famous as a champion of astrology. His best-known work was A Defence of Judiciall Astrologie (1603), the most substantial English defence of astrology of its day, rebutting John Chamber's A Treatise Against Judiciall Astrologie (1601), which had called for parliament to outlaw astrology. Heydon argued that it was a valid science, compatible with Christianity. He drew upon Tycho Brahe and others.
