Pensieve

The Pensieve is an object introduced in Harry Potter and the Goblet of Fire. Characters put their thoughts into it using their wand to syphon them from their head. They can then examine them from a third person veiw at any time. The first time Harry sees it, is in Dumbledore's office and it shows him his memory of Death Eaters' trials. There are others moments in which Harry uses the Pensieve but one of the more important memories is the one where Harry looks inside Severus Snape's pensieve, and sees his father James Potter, and his three friends Sirius Black, Remus Lupin and Peter Pettigrew while they joked with the professor. Dumbledore also uses one in Harry Potter and the Half-Blood Prince to show Harry how Tom Riddle grew into Voldemort