The Latin phrase gradus ad Parnassum means "a step towards Parnassus". [1] It is sometimes shortened to gradus. Parnassus is the prominence of a mountain range in central Greece, a few kilometres north of Delphi, of which the two summits, in Classical times, were called Tithorea and Lycoreia. In Greek mythology, one of the peaks was sacred to Apollo and the nine Muses, the inspiring deities of the arts, and the other to Dionysus.[2] The phrase came to be used by authors of various books of instruction with the aid of which gradual progress and mastery in an art or scholarly discipline is sought.