 Aristotle turns therefore, in X.7–8, to the two remaining alternatives—politics and philosophy—and presents a series of arguments to show that the philosophical life, a life devoted to theoria (contemplation, study), is best. Theoria is not the process of learning that leads to understanding; that process is not a candidate for our ultimate end, because it is undertaken for the sake of a further goal. What Aristotle has in mind when he talks about theoria is the activity of someone who has already achieved theoretical wisdom. The happiest life is lived by someone who has a full understanding of the basic causal principles that govern the operation of the universe, and who has the resources needed for living a life devoted to the exercise of that understanding. Evidently Aristotle believes that his own life and that of his philosophical friends was the best available to a human being. He compares it to the life of a god: god thinks without interruption and endlessly, and a philosopher enjoys something similar for a limited period of time.