HOGWARTS: A History

HOGWARTS FOUR

Hogwarts was founded over a thousand years ago (the precise date is uncertain) by the four greatest witches and wizards of the age. The four school Houses are named after them: Godric Gryffindor, Helga Hufflepuff, Rowena Ravenclaw, and Salazar Slytherin. They built Hogwarts together, far from prying Muggle eyes, for it was an age when magic was feared by common people, and witches and wizards suffered severe persecution.

For a few years, the founders worked in harmony together, seeking out the young who showed signs of magic and bringing them to the castle to be educated. But then disagreements sprang up between them. A rift began to grow between Slytherin and the others. Slytherin wished to be more selective about the students admitted to Hogwarts. He believed that magical learning should be kept within all-magic families. He disliked taking students of Muggle parentage, believing them to be untrustworthy. After a while, there was a serious argument on the subject between Slytherin and Gryffindor, and Slytherin left the school.

-- Harry Potter and the Chamber of Secrets