A passage from Marcus Aurelius
Marcus Aurelius, Meditations 2.16
✱
The soul of man does violence to itself, first of all, when it becomes an abscess, and, as it were, a tumour on the universe... Secondly, when it is averse from any man, or even moves towards him with the intention of injuring, such as are the souls of those who are angry.
Related passages
✱
Begin the morning by saying to thyself, I shall meet with the busy-body, the ungrateful, arrogant, deceitful, envious, unsocial.
✱
Take away thy opinion, and then there is taken away the complaint, 'I have been harmed.' Take away the complaint, and the harm is taken away.
✱
At dawn, when you have trouble getting out of bed, tell yourself: 'I have to go to work — as a human being.'