Illi qui sunt in aliqua excellentia, maxime irascuntur, si parvipendantur (puta si dives parvipenditur in pecunia, et rhetor in loquendo, et sic de aliis), quia constat quod quanto aliquis est excellentior, iniustius parvipenditur in hoc in quo excellit.
Those who excel in any matter, are most of all angry, if they be slighted in that matter (for instance, a wealthy man in his riches, or an orator in his eloquence, and so forth), because the more excellent a man is, the more unjust is a slight offered him in the matter in which he excels.
Causa irae in eo qui irascitur, ex parte dispositionis quae in eo relinquitur ex tali motivo. Manifestum est autem quod nihil movet ad iram, nisi nocumentum quod contristat. Ea autem quae ad defectum pertinent, maxime sunt contristantia, quia homines defectibus subiacentes facilius laeduntur. Et ista est causa quare homines qui sunt infirmi, vel in aliis defectibus, facilius irascuntur, quia facilius contristantur.
The cause of anger, in the man who is angry, may be considered on the part of the disposition produced in him by the motive aforesaid. Now it is evident that nothing moves a man to anger except a hurt that grieves him: while whatever savors of defect is above all a cause of grief, since men who suffer from some defect are more easily hurt. And this is why men who are weak, or subject to some other defect, are more easily angered, since they are more easily grieved.
Ille qui despicitur in eo in quo manifeste multum excellit, non reputat se aliquam iacturam pati, et ideo non contristatur, et ex hac parte minus irascitur. Sed ex alia parte, inquantum indignius despicitur, habet maiorem rationem irascendi. Nisi forte reputet se non invideri vel subsannari propter despectum, sed propter ignorantiam, vel propter aliud huiusmodi.
If a man be despised in a matter in which he evidently excels greatly, he does not consider himself the loser thereby, and therefore is not grieved, and in this respect he is less angered. But in another respect, insofar as he is more undeservedly despised, he has more reason for being angry; unless perhaps he thinks that he is envied or insulted not through contempt but through ignorance, or some other like cause.
Philosophus, in eodem libro, dicit quod homines propter excellentiam indignantur.
The Philosopher says (Rhet. ii, 9) that excellence makes men prone to anger.