Meditations 2.16

The soul of man does violence to itself, first of all, when it becomes an abscess, and, as it were, a tumor on the universe, so far as it can. For to be vexed at anything which happens is a separation of ourselves from nature, in some part of which the natures of all other things are contained. In the next place, the soul does violence to itself when it turns away from any man, or even moves towards him with the intention of injuring, such as are the souls of those who are angry. In the third place, the soul does violence to itself when it is overpowered by pleasure or by pain. Fourthly, when it plays a part, and does or says anything insincerely and untruly. Fifthly, when it allows any act of its own and any movement to be without an aim, and does anything thoughtlessly and without considering what it is, it being right that even the smallest things be done with reference to an end; and the end of rational animals is to follow the reason and the law of the most ancient city and polity.

Marcus Aurelius, Meditations 2.16, translated by George Long

The soul of man does wrong to itself then most of all, when it makes itself, as far as it can do so, an imposthume and as it were a malignant growth in the Universe. For to grumble at anything that happens is a rebellion against Nature, in some part of which are bound up the natures of all other things. And the soul wrongs itself then again, when it turns away from any man or even opposes him with intent to do him harm, as is the case with those who are angry. It does wrong to itself, thirdly, when it is overcome by pleasure or pain. Fourthly, when it assumes a mask, and in act or word is insincere or untruthful. Fifthly, when it directs some act or desire of its own towards no mark, and expends its energy on any thing whatever aimlessly and unadvisedly, whereas even the most trifling things should be done with reference to the end in view. Now the end for rational beings is to submit themselves to the reason and law of that archetypal city and polity—the Universe.

Marcus Aurelius, Meditations 2.16, translated by C. R. Haines