When you close your doors, and make darkness within, remember never to say that you are alone, for you are not alone; nay, God is within, and your genius is within. And what need have they of light to see what you are doing?

Watch yourself as you go about your daily business and later reflect on what you saw, trying to identify the sources of distress in your life and thinking about how to avoid that distress.

Truth is a thing immortal and perpetual, and it gives to us a beauty that fades not away in time, nor does it take away the freedom of speech which proceeds from justice; but it gives to us the knowledge of what is just and lawful, separating from them the unjust and refuting them.

Know, first, who you are, and then adorn yourself accordingly.

When a man is proud because he can understand and explain the writings of Chrysippus, say to yourself, 'if Chrysippus had not written obscurely, this man would have had nothing to be proud of.'

Progress is not achieved by luck or accident, but by working on yourself daily.

You ought to choose both physician and friend, not the most agreeable, but the most useful.