“Those who know, do. Those that understand, teach.”

Probable impossibilities are to be preferred to improbable possibilities.

If things do not turn out as we wish, we should wish for them as they turn out.

Nature does nothing uselessly.

Wishing to be friends is quick work, but friendship is a slow ripening fruit.

Happiness depends upon ourselves.

Wise men speak when they have something to say, fools speak because they have to say something.

It is not always the same thing to be a good man and a good citizen.

All human actions have one or more of these seven causes: chance, nature, compulsions, habit, reason, passion, desire.

Philosophy can make people sick.

The ultimate value of life depends upon awareness and the power of contemplation rather than upon mere survival.

The aim of the wise is not to secure pleasure, but to avoid pain.

We make war that we may live in peace.

You will never do anything in this world without courage. It is the greatest quality of the mind next to honor.

The energy of the mind is the essence of life.

A friend to all is a friend to none.

Excellence is an art won by training and habituation.