Aristotle: Nicomachean Ethics
Which of these two kinds of goods is the ultimate good?
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Aristotle says that the ultimate good must be something that is good in and of itself. This is a basic logical point, since by definition and ultimate good cannot be good for something outside of itself. Thus, Aristotle concludes that the ultimate good must be self-sufficient and final.
Aristotle, Nichomachean Ethics, Book I