(c. 50 – c. 135 AD) Greek Stoic philosopher.

First say to yourself what you would be; and then do what you have to do.
Everything which can make us better and happier was given to us by God. If our conscience is clear, then nothing can harm us.
I do not grieve that a person dies, that he loses his money, his estate, or all his property, all that can belong to a man. But it is a great pity when a person loses his greatest possession, his human dignity.
Do not be concerned too much with what will happen. Everything which happens will be good and useful for you.
Everyone knows that our habits are improved and strengthened through their exercise. In order to be a good walker, you need to walk a lot; in order to be a strong runner, you need to run frequently; in order to be a perceptive reader, you ought to read as much as you can. The same is true of your soul: if you become angry, you must know that you not only perform evil, but you also create an evil habit, and you increase your potential for further evil.
Let us think about God, remember Him, and talk to Him as often as we can.
Diogenes said, “A wise man becomes free when he is ready to die at any moment.” He wrote to the Persian king, “You cannot enslave truly free people, just as you cannot enslave a fish. You may capture them, but you cannot force them to serve; they prefer to die as captives. So, what would it profit you to imprison them?” This is a speech of a really free man, a man who recognizes his own freedom.
O God, while I stay on this earth I want to be that which I am.
Do you think that anybody can damage your soul? Then why are you so embarrassed? I laugh at those who think they can damage me. They do not know who I am, they do not know what I think, they cannot even touch the things which are really mine and with which I live.
Criticize yourself, but do not feel desperate about it.
If you throw some nuts and cookies on a road, you will eventually see children come, pick them up, and start to argue and fight for them. Adults would not fight for such things. And even children would not pick up the nuts’ empty shells. For a wise man, the wealth, the glory, and the rewards of this world are like sweets or empty shells on a road. Let the children pick them up and fight for them. Let them kiss the hands of the rich men, the rulers, and their servants. For the wise one, all these are but empty shells.