Its initial success helps to create the illusion that life is calculable. It tries to stockpile resources and skills, making certain that there are more than enough resources available to meet any threat. In a well-planned human life or organization, the threat is unknown but the resources are known. Sooner or later, for everyone, life simply and baldly presents a situation where the threat is overwhelming. It is concretely larger than I can knowingly handle, and my resources to face it are unknown.
Courage is the quality of spirit which addresses overwhelming situations.
Courage is the suspicion that adversity can evoke virtues not available in times of ease. It is the belief that there is a reservoir within oneself of spirit, uncontrollable but available, which can be called upon in crisis. You become a creature of your belief in possibility, in something which can pass through you and become eternal. None of this would happen if you were in control of the situation, or if you had any other alternative which seemed in the slightest way viable or decent. But the unseen bank account is one which has been testified to by others.