MAN A THINKING ANIMAL
Man fits into the scheme of nature as a "thinking animal". The mind, that which distinguished man as a rational being, is "incapable of being of being destroyed." It is a special part of the psyche or soul which in turn is the animating force of the body. The soul is the body's "form", and unlike Plato's soul, does not have an existence separate from the body. Thus it does not survive the death of the body. Yet it possesses both actuality and potentiality, and is the efficient, formal and final cause of the body. That is, it has a goal or end, and carries within it the means to that end.
MAN A POLITICAL ANIMAL
Man is also a "political animal". By this, Aristotle means Man lives best in a "polis", the city-state form of the Greek state. That is, he is characterized by living within a society with laws and customs. Man best fulfills his potential and natural end within a social context. This is the "good life". This is not a life of ease, but a life of virtue which results in the highest good, eudaimonia, or having a good spirit, often translated as happiness.
THE GOOD LIFE
Aristotle's "Ethics" is a study of choice in action; how should man best live? For Aristotle, this has a social as well as individual aspect. Some virtues, like courage and generosity, he describes as "practical" virtues, because they relate to man's social nature. The truly balanced individual also pursues the "theoretical" virtues which are related to man as a rational being. Ultimate happiness lies in pursuit of wisdom for its own sake.