On Anger, Book II, XX

But just as nature makes some men prone to anger, so there are many other causes which have the same power as nature.

Some are brought into this condition by disease or bodily injury, others by hard work, long watching, nights of anxiety, ardent longings, and love: and everything else which is hurtful to the body or the spirit inclines the distempered mind to find fault.

All these, however, are but the beginning and causes of anger.

Habit of mind has very great power, and, if it be harsh, increases the disorder.

As for nature, it is difficult to alter it, nor may we change the mixture of the elements which was formed once for all at our birth: yet knowledge will be so far of service, that we should keep wine out of the reach of hot-tempered men, which Plato thinks ought also to be forbidden to boys, so that fire be not made fiercer.

Neither should such men be overfed: for if so, their bodies will swell, and their minds will swell with them.

Such men ought to take exercise, stopping short, however, of fatigue, in order that their natural heat may be abated, but not exhausted, and their excess of fiery spirit may be worked off.

Games also will be useful: for moderate pleasure relieves the mind and brings it to a proper balance.

With those temperaments which incline to moisture, or dryness and stiffness, there is no danger of anger, but there is fear of greater vices, such as cowardice, moroseness, despair, and suspiciousness: such dispositions therefore ought to be softened, comforted, and restored to cheerfulness: and since we must make use of different remedies for anger and for sullenness, and these two vices require not only unlike, but absolutely opposite modes of treatment, let us always attack that one of them which is gaining the mastery.