You have one test, as sure as God, by which to recognize if what you learned is true. If you are wholly free of fear of any kind, and if all those who meet or even think of you share in your perfect peace, then you can be sure that you have learned God’s lesson, and not your own. Unless all this is true, there are dark lessons in your mind that hurt and hinder you, and everyone around you.
The absence of perfect peace means but one thing: You think you do not will for God’s Son what his Father wills for him. Every dark lesson teaches this, in one form or another. And each bright lesson with which the Holy Spirit will replace the dark ones you do not accept, teaches you that you will with the Father and His Son.
~ Jesus, A Course in Miracles