Luther still has the power to surprise and stun with his insights into human nature.  He has those insights because he was a student of the scriptures.  When we get mad at folks who irritate us, or when we have problems and get impatient, we blame the circumstances.  Luther says the circumstances show us what we are.  He says –
“Those speak foolishly who ascribe their anger or their impatience to such as offend them or to tribulation. Tribulation does not make people impatient, but proves that they are impatient. So everyone may learn from tribulation how his heart is constituted.”