Cognitive theories grew out of Gestalt psychology. Allen's work takes a psychological perspective that combines evolutionary theories with Gestalt psychology. In Europe introspection survived in Gestalt psychology. Abraham Luchins also studied problem solving from the perspective of Gestalt psychology. According to Gestalt psychology, perception is a whole. His work has no substantive relation to scientific Gestalt psychology. The extent to which Gestalt psychology influenced Gestalt therapy is disputed, however. Kurt Koffka attempted to make a multidisciplinary theory of art known as Aesthetic of Gestalt. In 1935 Koffka published his "Principles of Gestalt Psychology". Max Wertheimer was one of the three founders of Gestalt psychology. In any case it is not identical with Gestalt psychology. This concept became important in much of Gestalt theory and practice. In 1935, Koffka published his "Principles of Gestalt Psychology". It is a crucial building block to the foundation of Gestalt psychologists' concepts and applications. He was known worldwide for his philosophical and intellectually rigorous take on Gestalt therapy.