Langston Hughes

A physician is not angry at the intemperance of a mad patient, nor does he take it ill to be railed at by a man in fever. Just so should a wise man treat all mankind, as a physician does his patient, and look upon them only as sick and extravagant.

Sometimes the routes leading to feelings of anger are so convoluted and circuitous that it takes enormous skill to discern their original source, or fountainhead. But regardless of the reason for or the source of the anger or the relative ease or complexity in perceiving either the anger or its source - everybody, but everybody, gets angry.