1) To say that happiness is the supreme good that is generally agreed, and we need clearer account of what it is. This available if we find the function of a human being might this be? Living seems common to plants, but we are looking for something special we should set aside the life of nutrition and growth. Next would come some sort of sentient life, but this is common to horses, oxen and every animal. There remains some sort of active life of the rational part of the soul Suppose, then, that the function of a human being is an activity of the soul in accordance with, involving, reason. Now the function of an X and a good X are of the same kind st for example of a harpist and a good harpist this is true in all cases, when we add to the function the outstanding accomplishment diat comesponds to the virtue (the harpist's function is to play, that ofthe good harpist to play wel).So if the function of a human being to be a certain life, namely an activity of the soul and actions expressing reason, then the excellent man's function will to do this well and in fine way (each function being discharged well when performed in accordance with its special virtue). So it follows that the good for humankind is an activity of the soul in accordance with virtue (or if there are several virtues, in accordance with the best and most complete virtue). And we must add, in a complete life. For one swallow does not make a summer, nor does one day; and neither one day, nor a short time, is enough to make someone blessed and happy