An elemental is a mythic being described in occult and alchemical works from around the time of the European Renaissance and particularly elaborated in the 16th century works of Paracelsus. There are four elemental categories: gnomes, undines, sylphs, and salamanders. These correspond to the Classical elements of antiquity: earth, water, air and fire. Aether (quintessence) was not assigned an elemental. Terms employed for beings associated with alchemical elements vary by source and gloss.