The Phoenix as it is most commonly depicted is of Greek origin;
however, as is so often the case, the Greek myth is derived from the
Egyptian:

http://www.polarissite.net/LegendPhoenix.htm

"A similar mythological Egyptian bird was the Bennu, a heron-like
bird. The Bennu was born in a spice-lined nest in a sycamore tree. It
too made its own funeral pyre in which it died. Its first flight,
after being reborn, was accompanied by thousands of ordinary birds.
[...] The Bennu was sacred to Osiris and Ra, and a symbol of the Sun
and resurrection. It also represented the morning star.

"The Egyptian Phoenix was called the 'Lord of jubilees', and was
considered to be the ba (spirit) of the Sun God Ra. At one point in
the Book of the Dead, the deceased says, "I have gone forth as a
Phoenix." In Heliopolis, the Bennu was said to live in the
benbenstone (obelisk) or in the sacred willow.

"In Mesopotamian art, the Phoenix may have been symbolized by the
horned and winged solar disk. Ancient bas-reliefs show this winged
disk also having tail-feathers, legs, and claws of a bird. Often this
winged disk also had horns. The winged disk of Abura Mazdah on a
relief at Persepolis distinctly shows this disk with tail-feathers
and bird's legs and feet."

http://en.wikipedia.org/wiki/Bennu

"According to ancient Egyptian myth, the Bennu had created itself
from a fire that was burned on a holy tree in one of the sacred
precincts of the temple of Ra. Other versions say that the Bennu bird
burst forth from the heart of Osiris. The Bennu was supposed to have
rested on a sacred pillar that was known as the benben-stone. The
Egyptian priests showed this pillar to visitors, who considered it
the most holy place on earth."

When Harry was in dire straits in the Chamber of Secrets, Fawkes the
Phoenix suddenly appeared in a burst of fire, ON TOP OF A PILLAR.

http://www.freewebs.com/garyosborn/akh.htm

"Both the Benben stone and its related archetypal creature, the bennu
bird, (a Heron) which is often depicted perched on top of the
capstone of an obelisk (`sacred pillar' – shamanic), also represented
the `soul', the `divine spark' or `life force' that is said to reside
in every man and woman and inside the centre of the skull – hence the
placement of the Benben on top of the column, obelisk or pyramid
which represented the human spine and body. To the ancient Egyptians
the soul was known as the ba – which they believed was one's own link
to the source or Godhead known as the Akh. We will recall that among
the Pyramid Texts are the `glorifications' – the sabu (associated
with the star constellation of Orion - representing the soul of both
Osiris and Horus) which makes one into an Akh."

The image of a Phoenix, or winged disk, atop a pillar inevitably
recalls the image of a caduceus:

http://www.m-w.com/mw/art/caduceus.gif

which is also associated with much of the same functions: healing and
rebirth.

We possess more information about the Greek Phoenix:

http://www.polarissite.net/LegendPhoenix.htm

"The Phoenix was a graceful bird, with brilliant plumage and a
distinctive tuft of feathers at the back of its head. There are at
least three different descriptions of the plumage colors of the
Phoenix. One says that the head, breast, and back are scarlet or
reddish-gold, and the iridescent wings are many colors. Its feet are
a Tyrian purple hue, while its eyes are sea-blue. Another says the
body is plum-colored with a scarlet back and wing feathers, a golden
head, and a long tail of rose and azure. The third description states
that the Phoenix is a royal purple with a golden neck and head. It is
possible that these descriptions are of the Phoenix in various stages
of its life."

"When the Phoenix knew its time had come, it flew to Arabia where it
gathered myrrh, laudanum, nard, and cassia. Carrying a great load of
these fragrances in its wings, the Phoenix flew on to Phoenicia.
There, it chose the tallest palm tree and built a nest in it from the
essences it had brought. At the next dawn, the great bird faced the
rising Sun and sang in a beautiful voice. The heat of the Sun ignited
the fragrant spices, and the Phoenix died in its own funeral pyre.

"After nine days, a fledgling Phoenix rose out of the ashes. A few
days later, when its wings were strong enough, the young Phoenix
gathered the ashes of its parent and flew them to Heliopolis in
Egypt. Thousands of ordinary birds accompanied it on its journey.
There, the Phoenix put the ashes of its parent on the altar in the
Sun temple. Then it flew toward the east and its distant home.

"Other writers of the Phoenix story disagree on several points. Some
said that instead of flying to Phoenicia with its spices, the Phoenix
flew directly to the temple at Heliopolis and built its funeral pyre
on the altar there. Others believed that the priest of the Sun temple
gathered the spices and prepared the next for the Phoenix. A few
writers recorded that the Phoenix did not rise straight from the
ashes, but rather spent three days in a worm-like form before turning
into the glorious Phoenix.

"The Phoenix never died permanently. Legend says it existed when the
universe was created and that it knows secrets of life and
reincarnation even the deities do not know."

http://www.monstrous.com/monsters/phoenix.htm

"Wherever it is found, the phoenix is associated with resurrection,
immortality, triumph over adversity, and that which rises out of the
ashes. Thus it became a favorite symbol on early Christian
tombstones."

In Deathly Hallows, Harry's Golden Snitch contains a secret inside
that allows him to see and converse with his dead loved ones, and
also allows him to pass the terrors of the Dementors on his journey
to the Gate of Saturn. This secret can only be accessed when Harry
realises that he must soon die.

Unlike the Phoenix in CoS, the purpose of the Golden Snitch in DH is
not to rescue Harry from death, but to facilitate his sacrificial
death -- a complete reversal, at first glance. In reality, this
show's Harry's spiritual growth over the course of the books, as by
the end of DH he has BECOME the Phoenix, which must die to be reborn.

Bill