Because of the bad reputation the house has gotten, with most deatheaters, otherwise known as Voldemort supporters, hailing from the Slytherin house. He mostly doesn't want to be apart of the house because of Draco Malfoy. Draco Malfoy seems stuck up and rude, and Harry doesn't want to end up like him.
This line from "The Tempest" by Shakespeare is about <span>Prospero calling out to his brother. It describes how compassion of forgiveness is given and at the same time the justice that is carried out within the happenings of the play.</span>
