Back at the castle Harry dashes towards Dumbledore′s office and shows him the true memory. In it Tom Riddle is told what Horcruxes are. Dumbledore and Harry come to the conclusion that Voldemort split his soul into seven pieces. One of them had been in Riddle′s diary which was destroyed in Harry′s second year. Another piece of the soul had been in the ring of Slytherin which has been destroyed by Dumbledore.
The headmaster believes that Salazar Slytherin′s locket and the Hufflepuff′s cup are also Horcruxes. There might be more Horcruxes in objects which belonged to Ravenclaw or Gryffindor and finally Nagini herself is also a Horcrux.
He promises Harry to take him along for the chase for the next Horcrux. He tells Harry how important it is that he understands what the prophecy meant. Voldemort decided on his own that Harry is the one who is equal to him and this made him the only one who can defeat Voldemort.
