Harold S. Kushner on theories of life's quests

Terrible as it was, [Victor Frankl's] experience in Auschwitz reinforced what was already one of his key ideas: Life is not primarily a quest for pleasure, as Freud believed, or a quest for power, as Alfred Adler taught, but a quest for meaning. The greatest task for any person is to find meaning in his of her life. Frankl saw three possible sources for meaning: in work (doing something significant), in love (caring for another person), and in courage during difficult times. 

~ Harold S. Kushner, Man's Search For Meaning, Foreword, p. x