A wrong is unredressed when retribution overtakes its redresser. It is equally unredressed when the avenger fails to make himself felt as such to him who has done the wrong.
For one thing is needful: that a human being should attain satisfaction with himself, whether it be by means of this or that poetry or art; only then is a human being at all tolerable to behold. Whoever is dissatisfied with himself is constantly ready for revenge, and we others will be his victims, if only by having to endure his ugly sight.
Of ill-temper there are three kinds: irascibility, bitterness, sullenness. It belongs to the ill-tempered man to be unable to bear either small slights or defeats but to be given to retaliation and revenge, and easily moved to anger by any chance deed or word. Ill-temper is accompanied by excitability of character, instability, bitter speech, and liability to take offence at trifles and to feel these feelings quickly and on slight occasions.
...If I continued to harbour any hope for music it lay in the expectation that a musician might come who was sufficiently bold, subtle, malicious, southerly, superhealthy to confront that music and in an immortal fashion take revenge on it.
I consider it a mark of great prudence in a man to abstain from threats or any contemptuous expressions, for neither of these weaken the enemy, but threats make him more cautious, and the other excites his hatred, and a desire to revenge himself.
In revenge a man is but even with his enemy; for it is a princely thing to pardon, and Solomon saith it is the glory of a man to pass over a transgression.