1. The Prophecy about Harry and Voldemort
This prophecy, which was first revealed in *Harry Potter and the Order of the Phoenix*, is the core of the series' plot. It states:
> *"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 his 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."*
The prophecy is not fully revealed in *Half-Blood Prince*. We already know about its existence, but we don't learn the whole thing. It's important to remember that this prophecy is not about *what* will happen, but rather *who* will be involved. The prophecy doesn't foretell specific events, but rather names the players involved in the final conflict.
2. The Prophecy about Snape and Lily
This prophecy is revealed through Snape's memories in *Half-Blood Prince*. It is not directly related to the events of the story, but it provides critical backstory for Snape's actions and motivations. The prophecy is told by Trelawney:
> *"The Dark Lord will mark him as his 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 prophecy refers to Snape and Lily, and it suggests that Snape could have become the Dark Lord's equal. It also hints that he could have been the one to kill Voldemort. However, the full prophecy, as we see in the book, is never completed.
It's important to note that Trelawney herself is not aware of the significance of the prophecy. She is simply a conduit, and the true meaning is only revealed later.
In conclusion, the prophecy in *Half-Blood Prince* is primarily about the prophecy about Harry and Voldemort. The second prophecy, concerning Snape and Lily, is more about providing context for Snape's character and motivations.