Make it, therefore, your study at the very outset to say to every harsh external impression,

"You are an external impression and not at all what you appear to be."

After that examine it and test it by these rules which you have, the first and most important of which is this: Whether the impression has to do with the things which are under our control, or with those which are not under our control; and, if it has to do with some one of the things not under our control, have ready to hand the answer, "It is nothing to me.