We have to admit that no animal except humans can feel anger. Wild beasts and other creatures can't be angry because anger is the enemy of reason, and it can only exist where reason lives. Wild beasts have impulses, fury, cruelty, and a fighting spirit. But they don't have anger any more than they have luxury. Yet they do give in to certain pleasures with even less self-control than we do. Don't believe the poet who says: "The boar forgets his wrath, the stag forgets the hounds. The bear forgets how he leaped frantically among the herd." When he talks about angry beasts, he just means they're excited and stirred up. They know no more about being angry than they know about forgiving. Animals don't have human emotions, but they do have certain impulses that look similar to ours. If they could really feel love and hate, they would also be able to form friendships and enemies, to disagree and agree. You can see hints of these qualities in them, but properly speaking, all emotions — both good and bad — belong only to human hearts.
We must admit, however, that neither wild beasts nor any other creature except man is subject to anger: for, whilst anger is the foe of reason, it nevertheless does not arise in any place where reason cannot dwell. Wild beasts have impulses, fury, cruelty, combativeness: they have not anger any more than they have luxury: yet they indulge in some pleasures with less self-control than human beings. Do not believe the poet who says: "The boar his wrath forgets, the stag forgets the hounds. The bear forgets how 'midst the herd he leaped with frantic bounds." When he speaks of beasts being angry he means that they are excited, roused up: for indeed they know no more how to be angry than they know how to pardon. Dumb creatures have not human feelings, but have certain impulses which resemble them: for if it were not so, if they could feel love and hate, they would likewise be capable of friendship and enmity, of disagreement and agreement. Some traces of these qualities exist even in them, though properly all of them, whether good or bad, belong to the human breast alone.