Anger is the result of hurt pride, of injured self-love.  It is a violent and inordinate commotion of the soul that seeks to wreak vengeance for an injury done.  The causes that arouse anger vary infinitely in reasonableness, and there are all degrees of intensity.

The malice of anger consists wholly in the measure of our deliberate yielding to its promptings.  Sin, here as elsewhere, supposes an act of the will, A crazy man is not responsible for his deeds; nor is anyone, for more than what he does knowingly.

The first movement or emotion of irascibility is usually exempt of all fault; by this is meant the play of the passion on the sensitive part of our nature, the sharp, sudden fit that is not foreseen and is not within our control, the first effects of the rising wrath, such as the rush of blood, the trouble and disorder of the affections, surexcitation and solicitation to revenge.  A person used to repelling these assaults may be taken unawares and carried away to a certain extent in the first storm of passion, in this there is nothing sinful.  But the same faultlessness could not be ascribed to him who exercises no restraining power over his failing, and by yielding habitually fosters it and must shoulder the responsibility of every excess.  We incur the burden of God’s wrath when, through our fault, negligence or a positive act of the will, we suffer this passion to steal away our reason, blind us to the value of our actions, and make us deaf to all considerations.  No motive can justify such ignoble weakness that would lower us to the level of the madman.  He dishonors his Maker who throws the reins to his animal instincts and allows them to gallop ahead with him, in a mad career of vengeance and destruction.

Many do not go to this extent of fury, but give vent to their spleen in a more cool and calculating manner.  Their temper, for being less fiery, is more bitter.  They are choleric rather than bellicose.  They do not fly to acts but to desires and well-laid plans of revenge.  If the desire or deed lead to a violation of justice or charity, to scandal or any notable evil consequence, the sin is clearly mortal; the more so, if this inward brooding be of long duration, as it betrays a more deep-seated malice.

Are there any motives capable of justifying these outbursts of passion?  None at all, if our ire has these two features of unreasonableness and vindictiveness.  This is evil.  No motive, however good, can justify an evil end.

If any cause were plausible, it would be a grave injury, malicious and unjust.  But not even this is sufficient, for we are forbidden to return evil for evil.  It may cause us grief and pain, but should not incite us to anger, hatred and revenge.  What poor excuses would therefore be accidental or slight injuries, just penalties for our wrongdoings and imaginary grievances!  The less excusable is our wrath, the more serious is our delinquency.  Our guilt is double-dyed when the deed and the cause of the deed are both alike unreasonable.