A Sluggish Memory

Dumbledore shows Harry a tampered memory from Horace Slughorn. In the original memory, a young Tom Riddle asks Slughorn about Horcruxes. Slughorn, looking troubled, explains that a Horcrux is an object in which a wizard hides a piece of their soul, achieved through murder. Riddle then asks if it would be better to make multiple Horcruxes, specifically seven, the most magical number. Slughorn is horrified and cuts the conversation short. Dumbledore explains that Slughorn has altered the memory to hide his shame. He tasks Harry with retrieving the true, unaltered memory from Slughorn, as it is crucial to understanding Voldemort's plans.