This diary was thrown away after Severus Snape wrote his final entry. But, that wasn't the end. In 2017, this diary fell into the hands of Albus Severus Potter, during a meal at the Great Hall. Somehow, the diary managed to find its way to the Great Hall at Hogwarts, and into the hands of Severus Potter. However, after reading it, Albus Potter turned the book in to the current headmaster of Hogwarts. The diary was then returned to Albus Potter. One day, Harry Potter, Albus's dad, found the diary. Harry scolded Albus for not telling him about the diary. Later that day, Albus got taunted by his teaser of a brother, James. 

James had said, "Awwy, Awwy. Sevvy, Sevvy! Sevvy Ally got into trouble by the famous wizawd, Hawwy Potter! Ooooh! Poor Sevvy!"

Albus had quite  a response to the teasing. He screamed, "SILENCIO!!!", which silenced James. He pointed his wand straight at James's mouth, and since Albus screamed it so loudly, James wasn't able to make voice come out of his mouth. Only until Harry and Ginny had each made twenty-five countercurses was James able to talk.

Harry looked through the diary, and he was able to read the deepest thoughts of Severus Snape. He then fully understood the fact that Severus Snape was in love from an early start. He killed Dumbledore upon Dumbledore's own request.