My father was just 32 years old when he was diagnosed with acute leukemia. Weeks later he was in the hospital, informed that he would not be leaving. Miraculously the leukemia went into remission, and he lived another five years. Even as a child, though, I could clearly see that the man who returned from the hospital was not the same one who had left home. Before, he had been concerned mostly with work and material success; now he embraced religion and family. Getting a second, tenuous chance at life was a profound experience that deeply changed his values and behavior.
We deflect it with humor, hedge against it with good works, shun reminders of our animal nature. Yet we all share the reality of mortality, and we know it, try as we might to throttle our thoughts about it. Indeed, this simultaneous knowing and recoiling from our knowledge is a tension that will run throughout our life. Yet despite the significance of the subject, for most of its history psychology has left the matter of how mortal thoughts affect us almost completely unexplored—terror incognita.