Summa Theologica

We must next consider the contrary vices: (1) Anger that is opposed to meekness; (2) Cruelty that is opposed to clemency. Concerning anger there are eight points of inquiry:

(1) Whether it is lawful to be angry?

(2) Whether anger is a sin?

(3) Whether it is a mortal sin?

(4) Whether it is the most grievous of sins?

(5) Of its species;

(6) Whether anger is a capital vice?

(7) Of its daughters;

(8) Whether it has a contrary vice?