Martin Seligman

Martin Seligman founded the field of positive psychology in 2000, and has devoted his career since then to furthering the study of positive emotion, positive character traits, and positive institutions. It’s a fascinating field of study that had few empirical, scientific measures — traditional clinical psychology focusing more on the repair of unhappy states than the propagation and nurturing of happy ones. In his pioneering work, Seligman directs the Positive Psychology Center at the University of Pennsylvania, developing clinical tools and training the next generation of positive psychologists. (source)