Amazon.com: Books: Activity: The Theory, Methodology, and Problems Leontiev's psychology is closely related to that of Lev S. Vygotsky (1896-1934), father of the "cultural historical" or "sociocultural" or "sociocognitive" approach. There is no longer a need, however, to try to stress the importance of Vygotsky's works. He is described as "the Mozart of psychology" and his influence is dramatically growing (he is cited more than 5.600 times in the Social Sciences Citation Index, his "Collected Works" is published in six impressive volumes by Plenum Publ. Corporation; Routledge has published an impressive series of "L.S. Vygotsky: Critical assessments" (price 700$)and any course in developmental psychology these days introduces his thoughts, and they are also beginning to change the self-understanding of cognitive science in a fundamental way. So, Wygotsky is becoming main stream.