Any system of philosophy or mysticism which proposes to
   attain intercourse with God and superior spirits, and consequent
   superhuman knowledge, by physical processes, as by the theurgic
   operations of some ancient Platonists, or by the chemical processes of
   the German fire philosophers; also, a direct, as distinguished from a
   revealed, knowledge of God, supposed to be attained by extraordinary
   illumination; especially, a direct insight into the processes of the
   divine mind, and the interior relations of the divine nature.