"I must say a word about fear. It is life's only true opponent. Only fear can defeat life. It is a clever, treacherous adversary, how well I know. It has no decency, respects no law or convention, shows no mercy. It goes for your weakest spot, which it finds with unerring ease. It begins in your mind, always. One moment you are feeling calm, self-possessed, happy. Then fear, disguised in the garb of mild-mannered doubt, slips into your mind like a spy."
Doubt
Fear