If Slytherin had been troubled only by teaching the Muggle-born students to read and write, perhaps he might not have chosen to leave Hogwarts in the end.
In his eyes, those Muggle-born students were not only terribly dull; even harder to accept was their attitude toward the Papal Court.
Wizards today might find it hard to imagine just how much influence the Church had over Europe a thousand years ago. Even students who had received several years of education at Hogwarts still held deeply devoted religious beliefs.
Slytherin found that even when he used all kinds of evidence from history and the real world, he could hardly change the Muggle-born students' minds.
On the contrary, not only did these Muggle-born students hold fast to their faith, they even tried to spread the glory of the Lord within the school.
Besides infuriating Slytherin, this behavior also provoked the resentment of many Pure-blood wizards, eventually deepening the rift between them into an irreparable divide.
So Slytherin had been eager to simply get rid of those Muggle-born students whose minds were as stubborn as blocks of wood. He had voiced his dissatisfaction to the other Founders more than once.
He had proposed either banning the admission of any more foolish Muggle-born students or completely purging the school's atmosphere. Of course, by "purging," he meant taking certain rather extreme measures.
The other three Founders naturally opposed Slytherin's radical ideas, especially Gryffindor and Hufflepuff. They both hoped he would be more patient and give the Muggles time to change.
But after being tormented by the situation for years, Slytherin had come to believe deep down that, unless the Papal Court's influence over European society could be changed, there was no way to educate those Muggle-born students.
In the end, Slytherin's clashing ideals and frequent conflicts