Symbols are objects, characters, figures, or colors used to represent abstract ideas or concepts.
The Half-Blood Prince’s Potions Book quickly becomes one of Harry’s most prized possessions, not only because it helps him so much in Potions class, but because he feels an unspoken connection to its owner. At first, Harry believes that the book may have belonged to his father, and it becomes symbolic of how badly Harry wishes his parents were still alive. Hermione tries to convince Harry that the Prince could be a girl, and then Lupin tells Harry that he never heard James refer to himself as “Prince.” Finally, Harry figures out that the timing is off, and the book could never have belonged to his father. He is devastated. Later, when Harry finds out that the Half-Blood Prince is Snape, he is even more heartbroken.
With the help of Dumbledore’s Pensieve, Harry is made privy to various scenes from Voldemort’s past. Dumbledore believes that seeing these scenes will help Harry to better understand Voldemort and, consequently, destroy him. While Harry does learn quite a bit about Voldemort’s habits and vices, he also starts to understand how difficult Voldemort’s life was—like Harry, Voldemort was an orphan and felt that Hogwarts was his only true home. Harry also uses the Pensieve to learn about Voldemort’s interest in Horcruxes. Without these memories to sift through, gathered from friends and colleagues of Dumbledore’s, Harry would not know how to destroy Voldemort. Once again, Harry is unable to act on his own but must rely on the support and sacrifices of others.
Merope’s locket was once owned by Salazar Slytherin and boasts his mark. When Merope is pregnant with Voldemort, she is forced to sell the locket to Borgin and Burkes to get money for food and shelter, but she gets very little money in return, even though the shop owners know that it is nearly priceless. Later, when Voldemort gets a job working for the same shop, he discovers that the locket has been resold to a woman named Hepzibah Smith, whom Voldemort later murders, finally taking the locket back. Dumbledore believes it has been turned into a Horcrux, but when they venture out to collect it, it has already been taken. In many ways, Merope’s locket is Voldemort’s only remaining connection to his mother and takes on even greater significance than his other Horcruxes. It is appropriate, then, that it is the Horcrux that Dumbledore dies trying to recover.