Thirty dangerous seals

Giordano Bruno (1548-1600)
Explicatio triginta sigillorum ad omnium scientiarum et artium inventionem dispositionem et memoriam…
London, John Charlewood?, ca 1583

These diagrams are part of Bruno’s ideas in mnemonics and logic; in other contemporary works he suggested remarkably modern ideas of heliocentricity, mechanics and the plurality of worlds. Finding himself out of sympathy with thinkers on the continent, Bruno arrived in England in April 1583 where, it seems, he published his Sigillus sigillorum and this, the Explicatio triginta sigillorum (or Explanation of thirty seals), mystical works about logic, mnemonics and the Art of remembering, all part of Bruno’s philosophical world. Many of his ideas chimed well with modern thinking, on heliocentricity, mechanics and the plurality of worlds, and together caused him to fall foul of the Roman Inquisition on numerous heretical grounds. He was arrested, tried, and executed by burning at the stake in 1600 and his works placed in the Index librorum prohibitorum.