ENIGMA, a riddle or puzzle, especially a form of verse or prose composition in which the answer is concealed by means of metaphors. Such were the riddle of the Sphinx and the riddling answers of the ancient oracles. The composition of enigmas was a favourite amusement in Greece and prizes were often given at banquets for the best solution of them (Athen. x. 457). In France during the 17th century enigma-making became fashion able. Boileau and J. J. Rousseau did not consider it beneath their literary dignity. The word is applied figuratively to any thing inexplicable or difficult of understanding.