Mistress Nata did not like how slow this student was. He was making her take a lot of time on one subject and he was, as a result, dragging the entire class behind. The mistress had to find a way to make him work harder and be at the level of the rest of the class. That way, learning would be faster for everyone. She got him to do that by humiliating him with dirty feet a few times a week until he changed.