Nicomachean Ethics
Happiness

Finally, Aristotle returns to eudaimonia, the aim of the whole Ethics. According to the Book I definition it is an activity, good in and of itself, and chosen for its own sake (not instrumentally). Aristotle argued that virtues fit this definition, but perhaps recreational activity also fits the bill (a tennis game, for example, may be played for its own sake).

Aristotle thinks that this trivializes eudaimonia. Anybody can enjoy recreation, even a slave, and no one would want to be a slave. He believes recreation is not an end in itself, but a way of relaxing in preparation for (or to recover from) more noble activity: in other words it is instrumental.

Aristotle says that if perfect eudaimonia is activity in accordance with the highest virtue, then this highest virtue must be the virtue of the highest part of the soul. He says this must be the intellect (nous) "or whatever else it be that is thought to rule and lead us by nature, and to have cognizance of what is noble and divine". This highest activity, Aristotle says, must be philosophical contemplation (energeia... theōrētikē). This is also the most sustainable, pleasant, self-sufficient activity; and it is chosen for its own sake. To achieve it means to live in accordance with something immortal and divine which is within humans, and, "so far as we can, make ourselves immortal, and strain every nerve to live in accordance with the best thing in us". According to Aristotle, contemplation is the only type of happy activity in which the gods might be imagined to engage in. The intellect is the true self, and this type of happiness is the happiness most suited to humans, in that only humans possess both happiness (eudaimonia) and the intellect (nous). Aristotle also claims that compared to other virtues, contemplation requires the least in terms of possessions and allows the most self-reliance, "though it is true that, being a man and living in the society of others, he chooses to engage in virtuous action, and so will need external goods to carry on his life as a human being".

What distinguishes humans from other animals is that we reason. This is a hint to our purpose. And that in turn tells us how to fulfill our eudaimonia. "That which is proper to each thing is by nature best and most pleasant for each thing; for man, therefore, the life according to reason is best and pleasantest, since reason more than anything else is man. This life therefore is also the happiest." Indeed, eudaimonia itself is something peculiar to human beings, and this is fundamental:

Happiness extends... just so far as contemplation does, and those to whom contemplation more fully belongs are more truly happy, not as a mere concomitant but in virtue of the contemplation; for this is in itself precious. Happiness, therefore, must be some form of contemplation.
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