In his famous book, Man's Search for Meaning, Dr. Viktor Frankl, a survivor of Nazi concentration camps, wrote of his horrific experiences during World War II. Frankl, a psychiatrist by profession, approached his imprisonment with a scientist's analytical mind. He observed that those prisoners who had a clear goal, or a cause greater than themselves, were the ones most likely to carry on and survive—even in the midst of sadistic brutality and cruel deprivation. Those without such a purpose were most likely to perish. Frankl concluded that, as the philosopher Nietzsche observed, "He who has a why to live for can bear with almost any how."