[...] the serpent's evil is motiveless or, at best, arises out
of mere delight in mischief. The Jews of post-Exilic times made this
seem more reasonable, however, by equating the serpent with Satan, who
is the spirit of Evil as God is the spirit of Good. (This notion was
derived from Persian religious thought [...].)Actually, the tale of the serpent is quite un-Biblical in atmosphere.
Only here and in one other case (that of Balaam's ass [...]) do the
Hebrew scriptures mention talking animals. It seems quite likely that
the tale of the serpent is extremely primitive and represents a
remnant of nature myth [...].
The serpent is a particularly important animal in religious ritual,
whether for good or evil. The fact that a serpent moves in so quiet
and hidden a fashion and strikes so suddenly and so unexpectedly with
so poisoned a fang, makes it an obvious representation of cunning and
evil. It is such a representation of cunning evil in the story of the
garden of Eden [...]
Something that is dangerous and evil is to be feared, and something
that is feared had better be treated well and propitiated, so that
serpents could be worshiped even while dreaded.
Then, too, the serpent is looked upon as symbolizing immortality
because of its ability to shed its skin. Any primitive man, observing
the process by which a serpent sheds an old, dull skin and emerges in
a new, bright colored one, might be excused if he assumed the serpent
had undergone a process of rejuvenation. [...]
Thus, in the Gilgamesh legend [...], when the hero finally gains the
plant that brought immortality, he has it stolen from him by a
serpent, which then becomes immortal. (In the garden of Eden, it is
the serpent who steals immortality from Adam and Eve, although it is
not itself made immortal as a result, but is punished.)