For Aristotle, happiness corresponds to the highest kind of virtue. In Book I of his Nicomachean Ethics, Aristotle treats practical virtues, and in Book X, he treats theoretical contemplation as the best practice that might guarantee happiness. Thus, Aristotle might be said to have given two answers (naturalistic and theological) to the question of the nature of happiness. This is because the self-sufficient character of happiness implies its intrinsic value, and practical activities— which are deemed intrinsically valuable in Book I are treated as having secondary value, in Book X, as a means to the higher (theoretical) happiness. Some people believe that Aristotle has finally failed to remain committed to the distinction between intrinsic and instrumental good, falling into a contradiction in his definition of happiness. In this paper, in the first place, we draw on the analytic method and revisit the notion of kalon to show that the function of theoretical reason in acquisition of moral virtues goes beyond what is claimed by naturalistic readings. Indeed, happiness is fundamentally a theological property. Secondly, we outline two senses of self-sufficiency (the dominant end, and the comprehensive end) to suggest that the second sense enables us to reconcile the two notions of “ being secondary or subsidiary” and “ being done for its own sake, ” in which case a proper reply might be yielded for the problem of contradiction.