The energy or active exercise of the mind constitutes life.

Anybody can become angry - that is easy, but to be angry with the right person and to the right degree and at the right time and for the right purpose, and in the right way - that is not within everybody's power and is not easy.

In all things of nature there is something of the marvelous.

Men cling to life even at the cost of enduring great misfortune.

The moral virtues, then, are produced in us neither by nature nor against nature. Nature, indeed, prepares in us the ground for their reception, but their complete formation is the product of habit.

The happy life is thought to be one of excellence; now an excellent life requires exertion, and does not consist in amusement.

The greatest virtues are those which are most useful to other persons.

The one exclusive sign of thorough knowledge is the power of teaching.

The educated differ from the uneducated as much as the living from the dead.