Fludd or Flud, Robert, 1574–1637, English mystic philosopher. Educated at Oxford and on the Continent, he became a London physician. Strongly influenced by the mystical doctrines of Paracelsus, he attempted to reconcile these speculations with the new science of the 17th cent. From his study of Paracelsus he arrived at the theory that spiritual and physical truth are identical. His mystical pantheism centered in God as the all-pervading form of which the world and man are manifestations. He held that the dualism of light and darkness is inherent in all things. The best-known English representative of the Rosicrucians, he spread their ideas in a number of medico-theosophical books. His major works include Utriusque cosmi, maioris scilicet et minoris, metaphysica, physica atque technica historia (1617–21) and Philosophia Moysaica (1638; tr. Mosaicall Philosophy, 1659).
See F. A. Yates, Theatre of the World (1969); W. Huffman, Robert Fludd and the End of the Renaissance (1989).