The Good of man is the active exercise of his soul's faculties in conformity with excellence or virtue, or if there be several human excellences or virtues, in conformity with the best and most perfect among them.

Nicomachean Ethics (1934 translation by H. Rackham), book 1, chapter 7, section 15, p. 33. President John F. Kennedy often paraphrased this idea. On May 8, 1963, he said to a group of foreign students: "The ancient Greek definition of happiness was the full use of your powers along lines of excellence". The Public Papers of the Presidents of the United States: John F. Kennedy, 1963, p. 380.