Thoughts can give life. Thoughts can kill. For example, a soldier. The Torah commands a soldier at war, “Do not allow your heart to weaken. Do not fear. Do not panic.” Imagine this: An army is racing towards you. Your eyes have witnessed their savagery. How can you command your heart not to fear? Maimonides explains: Don't think those thoughts and you will not fear. Dodge them as you dodge a flying arrow. Because such thoughts threaten not only your...