Aristotle's two accounts of the nature of happiness in Nicomachean Ethics i and x have caused much disagreement concerning the precise constitution of human goodness, or happiness (eudaimonia). While all may agree that happiness is an activity of the soul, the question remains concerning the exact relation between the moral and intellectual virtues, or the practical and theoretical life. H. G. Gadamer here notes the tension in the two accounts:

Even as astute a reader of Aristotle as Gadamer has difficulty in determining the importance of some human accomplishments in relation to others. The assertion that both practical wisdom (phronesis) and intellectual wisdom (sophia) comprise the supreme good, and that both must be considered as the highest virtue, needs careful consideration. The uncertainty concerning the relation between the practical and the theoretical has a firm basis in Aristotle's text, and Gadamer's approach seems close to what Aristotle may have intended.

In the last chapters of the N.E. Aristotle praises the perfection of the intellect, the purely rational part of the soul, as the highest human achievement. This is the clearest expression of the supremacy of the theoretical life, and its dominant role in the production of happiness. If contemplation is supreme, then all other actions and pursuits must be directed toward the contemplative life. Only contemplative activity would merit the designation ‘supremely good’, since it not only perfects the best part of human beings, but its objects are also knowable in themselves (1177a19–22). Contemplation is the most continuous, independent and self-sufficient of human accomplishments, since it demands nothing outside the intellectual fervor and excellence of the contemplative. Aristotle can think of nothing more desirable than the pleasure of contemplating truth (1177a23).