The passion of anger is the desire to revenge ourselves on those who have hurt us.
In the beginning, when we feel the anger welling up, we are able if we are monks to intercept this beginning and to cut this anger off. But we have been injured, perhaps only in our self-esteem, and we want to protect ourselves, even if it is only in our self-esteem, and we allow the anger to continue. Having enjoyed, then, the pleasure of anger, we are agitated, sometimes for a day or three.
In modern terms, anger has much to do with conflict: conflict with other people, conflict with the elements, conflict with God. Characteristic of the demons is their anger. Characteristic of man is desire (sexual desire). Characteristic of the angels is mind or nous: the angels are always engaged in contemplation, a matter of the mind or nous. What the monk must do is head for the angels, not for the demons.