“...'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.” HogwartsGryffindorSlytherinMuggle Born Book:Harry Potter and the Chamber of Secrets Source: Harry Potter and the Chamber of Secrets