Marble relief, produced by a neo-Attic workshop and dating back to the
Roman Imperial Age, recovered in the XVIII century near Naples and subsequently
acquired by the Vatican Museums. The relic shows two Maenads, followers
of Dionysus, beside a bull, which probably represents one of the various
manifestations of the god himself. Dionysus was often called with the
epithet of Eiraphiótes, a term of obscure meaning. It seems,
however, that it could be referred to an animal form of the god and
related to an Indo-European root, common to the Sanskrit rsabhá
(“bull”), assuming in this way the meaning of “god
who reveals himself in the aspect of a bull” (Chantraine, 1968,
p.323; Cassola, 1994, p.463-64). A peculiar characteristic of Dionysos
is his polymorphism, that is, his capacity to present himself under
multiple aspects. He is depicted sometimes as a child, sometimes as
a young adolescent, or as a bearded adult, and is deemed with the ability
to turn himself into the shape of various animals, thus distinguishing
him from the other Olympians. In an Homeric hymn to Dionysus, it is
told how the god, in his aspect of a youth, was abducted by a ship of
Tyrrhenian pirates. During the sailing, Dionysus made vine branches
grow around the mast of the ship, turning himself into a fierce lion.
The pirates, terrified, plunged into the sea and were transformed in
their turn into dolphins.
[Source: http://www.crystalinks.com/bacchus.html]