THE GREEK HEROES 95 bound to the horns of a bull. Just then the sons learned from their foster father the secret of their origin, rescued their mother, and visited the cruel punishment with which she had been menaced upon Dirce herself, who after her death was changed into a spring near Thebes. The fastening of Dirce to the bull was represented in the second century B.C. by Apollonius and Tauriscus of Tralles in the marble group commonly known as "the Farnese bull," which is now in Naples. The twin brothers obtained the sovereignty in Thebes, and surrounded the lower city with a wall in which were seven gates. The stones dragged along by the powerful Zethus piled themselves up in layers regularly of them- selves by the magic of Amphion's playing on the lyre, a legend that was probably intended to glorify the regulating power of music, in which the same symmetry prevails as in architecture. 125. Amphion wedded the daughter of Tantalus, Niobe, who had inherited from her father conscious pride. When she had borne six sons and six daughters, she boasted that she was richer than Leto, who had but two children. Apollo and Artemis, however, revenged the insult offered their mother, by killing the children of Niobe, who in grief at their loss was turned into stone and removed to Mount Sipylus in Lydia; whereupon Amphion put him- self to death. A representation of the killing of the children of Niobe was executed by Scopas or Praxiteles, probably for the city of Seleucia in Cilicia. This group was later brought to Rome. We are acquainted with most of its figures through Eoman copies (the most complete group of which is in Florence).
