Prof. Dr. Franz Vesely · CC BY-SA 3.0 de

Viktor Frankl developed logotherapy, a school of psychotherapy built on the idea that the search for meaning, not pleasure or power, is the central human drive — a theory he refined while imprisoned in Nazi concentration camps. Man's Search for Meaning, his account of that experience paired with his psychological framework, became one of the best-selling books of the twentieth century. He wrote 39 books over the course of his career.