Aristotle, Nicomachean Ethics 1097b-1098a
“Doesn’t it seem that, just as the eye, hand, foot, and every part of the body has a purpose, so too there must be some task beyond all these together for a human being? What then could this be? For simply to live seems shared with plants too—we are looking for humanity’s particular purpose. The survival functions of nourishment and growth should just be set aside.
Following this, some might emphasize the function of sentience—but this seems common too with a horse, a cow and nearly every animal. What is left is the practice from human’s having reason. Of this, we have the part that heeds reason, and the part that possesses it and uses it. What this means can again be divided according to practice—for this seems to be the more proper way to say it.
If the task of the human soul is the practice according to reason rather than without reason, and we say that a task is the same in general for a group as it is for its serious members—just as it will be for a harp player in general the same as for a serious harpist once we accept that the excellence of the task is defined by its particular virtue: it is the task of a harpist to play the harp, the serious one plays it well—if this principle is true, and we propose that the task of a human being is some kind of life, and that life in this regard is the practice of the soul and actions performed with reason, and that the serious person does these things well and nobly, and each thing will be done well according to its intrinsic virtue—if all this is so, then the human good is the exercise of the soul through its own virtue—and if there are multiple kinds of virtues, then it is in accord with the best and most complete of them.
And, still, this happens over a full lifetime. For, one swallow does not make it spring, nor even one day; and thus, neither does one day or any brief amount of time make someone blessed and happy.”
ἢ καθάπερ ὀφθαλμοῦ καὶ χειρὸς καὶ ποδὸς καὶ ὅλως ἑκάστου τῶν μορίων φαίνεταί τι ἔργον, οὕτω καὶ ἀνθρώπου παρὰ πάντα ταῦτα θείη τις ἂν ἔργον τι; τί οὖν δὴ τοῦτ’ ἂν εἴη ποτέ; τὸ μὲν γὰρ ζῆν κοινὸν εἶναι φαίνεται καὶ τοῖς φυτοῖς, ζητεῖται δὲ τὸ ἴδιον. ἀφοριστέον ἄρα τήν τε θρεπτικὴν καὶ τὴν αὐξητικὴν ζωήν. ἑπομένη δὲ αἰσθητική τις ἂν εἴη, φαίνεται δὲ καὶ αὐτὴ κοινὴ καὶ ἵππῳ καὶ βοῒ καὶ παντὶ ζῴῳ. λείπεται δὴ πρακτική τις τοῦ λόγον ἔχοντος· τούτου δὲ τὸ μὲν ὡς ἐπιπειθὲς λόγῳ, τὸ δ’ ὡς ἔχον καὶ διανοούμενον. διττῶς δὲ καὶ ταύτης λεγομένης τὴν κατ’ ἐνέργειαν θετέον· κυριώτερον γὰρ αὕτη δοκεῖ λέγεσθαι. εἰ δ’ ἐστὶν ἔργον ἀνθρώπου ψυχῆς ἐνέργεια κατὰ λόγον ἢ μὴ ἄνευ λόγου, τὸ δ’ αὐτό φαμεν ἔργον εἶναι τῷ γένει τοῦδε καὶ τοῦδε σπουδαίου, ὥσπερ κιθαριστοῦ καὶ σπουδαίου κιθαριστοῦ, καὶ ἁπλῶς δὴ τοῦτ’ ἐπὶ πάντων, προστιθεμένης τῆς κατὰ τὴν ἀρετὴν ὑπεροχῆς πρὸς τὸ ἔργον· κιθαριστοῦ μὲν γὰρ κιθαρίζειν, σπουδαίου δὲ τὸ εὖ· εἰ δ’ οὕτως, [ἀνθρώπου δὲ τίθεμεν ἔργον ζωήν τινα, ταύτην δὲ ψυχῆς ἐνέργειαν καὶ πράξεις μετὰ λόγου, σπουδαίου δ’ ἀνδρὸς εὖ ταῦτα καὶ καλῶς, ἕκαστον δ’ εὖ κατὰ τὴν οἰκείαν ἀρετὴν ἀποτελεῖται· εἰ δ’ οὕτω,] τὸ ἀνθρώπινον ἀγαθὸν ψυχῆς ἐνέργεια γίνεται κατ’ ἀρετήν, εἰ δὲ πλείους αἱ ἀρεταί, κατὰ τὴν ἀρίστην καὶ τελειοτάτην. ἔτι δ’ ἐν βίῳ τελείῳ. μία γὰρ χελιδὼν ἔαρ οὐ ποιεῖ, οὐδὲ μία ἡμέρα· οὕτω δὲ οὐδὲ μακάριον καὶ εὐδαίμονα μία ἡμέρα οὐδ’ ὀλίγος χρόνος.