We should also note the importance of the concept of telos, which we might translate as “end” or “goal.” The first sentence of the Ethics tells us that every activity aims at a certain telos. For instance, one might go to the gym with the telos of becoming fitter. When Aristotle identifies happiness as the highest goal, he is claiming that happiness is the ultimate telos of any action. We might understand this idea of an ultimate telos by imagining the child who constantly asks, “why?”:

“Why are you going to the gym?”

“To become fitter.”

“Why do you want to become fitter?”

“So that I’ll be healthier.”

“Why do you want to be healthy?”

“So that I’ll live longer and have more energy.”

“Why do you want a long and energetic life?”

“Because that makes for a happy life.”

“Why do you want a happy life?”

“I just do.”

Every activity has a telos, which is an answer to the question, Why are you doing this? Happiness is the ultimate telos because there is no further telos beyond happiness and because the ultimate goal of all our other activities is happiness.

For Aristotle, the soul, or psuche (the root of our word psychology), is simply that which distinguishes living things from nonliving things. All living things have a nutritive soul, which governs bodily health and growth. Animals and humans differ from plants in having an appetitive soul, which governs movement and impulse. Humans differ from animals in also having a rational soul, which governs thought and reason. Because rationality is the unique achievement of humans, Aristotle sees rationality as our telos: in his view, everything exists for a purpose, and the purpose of human life is to develop and exercise our rational soul. Consequently, a human can “be human” well by developing reason in the way that a flutist can be a good flutist by developing skill with the flute.