By itself,” he said, “pain is not always enough. There are occasions when a human being will stand out against pain, even to the point of death. But for everyone there is something unendurable – something that cannot be contemplated. Courage and cowardice are not involved. If you are falling from a height it is not cowardly to clutch at a rope. If you have come up from deep water it is not cowardly to fill your lungs with air. It is merely an instinct which cannot be destroyed.