insights on fear [from life of pi]

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. 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 meets disbelief and disbelief tries to push it out. But disbelief is a poorly armed foot soldier. Doubt does away with it with little trouble. You become anxious. Reason comes to do battle for you. You are reassured. Reason is fully equipped with the latest weapons technology. But, to your amazement, despite superior tactics and a number of undeniable victories, reason is laid low. You feel yourself weakening, wavering. Your anxiety becomes dread. — Yann Martel, Life of Pi