In later art the serpent appears as a tempter. The Brazen Serpent of the Hebrews that gave newness of life to those who, bitten by the fiery dragon, raised their eyes to it, is an anticipation of the Crucifixion.
The mythical dragon is a Middle Age symbol of sin in general and Paganism in particular. The Celtic use of the word for “a chief” is the source of the legendary dragon slayer, as a knight killing a chief thereby slew a dragon.
The dragon, which appears as a guardian, as in the garden of the Hesperides, watching the tree bearing the golden apples of Hera, is also a poetic allusion to flood or inundation.
The tradition of the Python and Apollo is an instance of poetic allusion to the power of the sun drying up the overflow, as also the deliverance of the city of Rouen by St. Romanus from the dragon Gargouille (waterspout) which lived in the Seine.
In Art and Literature traditions and legends dealing with probable occurrences have been handed down--in many cases completely transformed--by reason of this poetic license; _e.g._, the legend of Marsyas the Phrygian flute-player, who, challenging Apollo to a contest of skill and being beaten, was flayed alive for his presumption.
The story is not without its moral, as the flute on which he played was one thrown away by Athenē, and, filled with the breath of that goddess, still discoursed sweet music. The story is based upon the respective superiority of the instruments--the Dorian mode in the worship of Apollo employing the lute or lyre, and the Phrygian mode in the worship of Cebele the flute, the reeds of which grew on the banks of the river Marsyas.
Another example is the tradition of the Danaides, daughters of Danaos, King of Argos, who, fifty in number, married the fifty sons of Ægytos. All but one murdered their husbands on the wedding night, and were punished in the infernal regions by having to draw water everlastingly in sieves from a deep well.
The literal explanation is that the followers of Danaos taught the Argives to dig wells and irrigate the land in the Egyptian manner. The soil of Argos, being dry and porous, resembling a sieve.
The extreme of poetic license is perhaps reached in the tradition of Geryon, a human monster with three bodies and three heads, whose oxen fed on human flesh and were guarded by a two-headed dog--both slain by Hercules. This is a fanciful account of the defeat of Geryon, who reigned over three kingdoms and had an ally who was at the head of two tribes.