"The one with the power to vanquish the Dark Lord approaches... born to
those who have thrice defied him, born as the seventh month dies... and the Dark
Lord will mark him as equal, but he will have power the Dark Lord knows not...
and either must die at the hand of the other for neither can live while the
other survives... the one with the power to vanquish the Dark Lord will be born
as the seventh month dies..."
Let's break the prophecy down:
The person who can defeat Voldemort will be born to parents
who have escaped Voldemort three times
They will be born near the end of July
Voldemort will mark them as equal in some way
They will have a power that Voldemort will not know about
Either they will kill Voldemort or Voldemort will kill them in the end,
because they cannot both exist
Although you should never trust a
character's word, Dumbledore is nearly always right and so we should assume the
person who can defeat the Dark Lord is Harry. In that case, he was born on July
31st (as the seventh month dies), he was marked by Voldemort (his lightning bolt
scar), he has a power Voldemort doesn't know about (the locked room in the
Department of Mysteries), and Lily and James have apparently defied Voldemort
three times. (We aren't sure what the three times are yet, this may be where the
Lupin-is-James theory comes in.) The only thing that hasn't come true is the part
about either Harry or Voldemort dying. Since the rest of the prophecy has come
true, we can probably assume that this part will happen. Note: We are
assuming these events are what the prophecy means. There is, of course, a chance
that the marking is not the lightning bolt scar, but this is very
unlikely.
It's important to note that Professor Trelawney was the one who first foretold the prophecy.
Although Dumbledore says they are "real" prophecies,
given her past reputation, it should be taken with a grain of salt.
However, a running piece through HP is the subject of things being "written in
the stars" and it seems likely that this prophecy will be fulfilled in its
entirety.
Now, given the conclusions on the "How Prophecies Work" page, we
could say that no matter what either Harry or his friends do, either Harry or
Voldemort WILL die in the end, slain by the other. In the back of my mind,
I keep remembering Dumbledore's words that choices are the things that make us
who we are, so perhaps this part of the prophecy can be changed, disproving the
ideas about prophecies being the absolute and concrete truth of what will
happen.