To Unlearn is as hard as to Learn

The beauty of the soul shines out when a man bears with composure one heavy mischance after another, not because he does not feel them, but because he is a man of high and heroic temper.

Now that practical skills have developed enough to provide adequately for material needs, one of these sciences which are not devoted to utilitarian ends [mathematics] has been able to arise in Egypt, the priestly caste there having the leisure necessary for disinterested research.

It is the mark of an educated mind to be able to entertain a thought without accepting it.

In a word, acts of any kind produce habits or characters of the same kind. Hence we ought to make sure that our acts are of a certain kind; for the resulting character varies as they vary. It makes no small difference, therefore, whether a man be trained in his youth up in this way or that, but a great difference, or rather all the difference.

Accordingly, the poet should prefer probable impossibilities to improbable possibilities. The tragic plot must not be composed of irrational parts.

A king ruleth as he ought, a tyrant as he lists, a king to the profit of all, a tyrant only to please a few.