Aristotle, answered from the texts and cited to the page.
The contemplative life (theoria) is the supreme activity and the highest happiness. The argument: happiness is activity in accordance with virtue and the best activity is activity in accordance with the best virtue; the best part of us is the nous (intellect), and its highest activity is contemplation of eternal truths; therefore the contemplative life is the highest happiness.12
Contemplation is also self- sufficient (the philosopher needs less than the practical person to do his characteristic activity), continuous (it can be pursued at length without exhausting), pleasant (the pleasure of contemplation is the purest), and chosen for itself (not as means to anything further). The political and moral virtues are also genuine excellences and constitute the form of flourishing available to most people most of the time, but the contemplative life is the activity of what is most divine in us and is therefore the highest. The unmoved mover thinks itself eternally; we approximate that activity to the extent that human nature permits.345
Whether it be reason or something else that is this element which is thought to be our natural ruler and guide and to take 1s thought of things noble and divine, whether it be itself also divine or only the most divine element in us, the activity, f of this in accordance with its proper virtue will be pertecee / happiness.Nicomachean Ethics, p. 216
Therefore the activity of God, which surpasses all | others in blessedness, must be contemplative; and of human ~ activities, therefore, that which is most akin to this must be most of the nature of happiness. This is indicated, too, by the fact that the other animals have no share in happiness, being completely deprived of such activity.Nicomachean Ethics, p. 220
It is to be expected, then, that, as different things seem valuable to boys and to men, so they 1 1095" 31-1096 2, 1098" 31-1099? 7. 2 1098# 5-7. should to bad men and to good.Nicomachean Ethics, pp. 215–216
Hence the good itself would be > this: the goal of all that is achievable by human action. This is > what falls under the science that has authority over all sciences; > this science is politics and household management and wisdom. Introduction > These states differ from the rest in being of that sort. Whether > they differ at all from one another must be considered later.Eudemian Ethics, p. 19
The first mover, then, exists of necessity; and in so far as it exists by necessity, its mode of being is good, and it is in this sense a first principle. For the necessary has all these senses-that which is necessary perforce because it is contrary to the natural impulse, that without which the good is impossible, and that which cannot be otherwise but can exist only in a single way.Metaphysics
Among the most contested doctrines in Aristotle's ethics, both within and beyond the Aristotelian tradition. The medieval reception Christianized the doctrine into the beatific vision (Aquinas). Modern democratic and Marxist critics object to the elitism: the contemplative life is available only to those with the leisure to pursue it, and its supremacy implicitly devalues the practical lives of those who lack that leisure. Within contemporary virtue ethics the debate runs between defenders (Hutchinson, Lear, who argue the supremacy of theoria is internal to the function argument) and revisionists (Nussbaum, Hursthouse, who argue practical and theoretical lives are equally complete forms of flourishing).