This book is about L. S. Vygotsky, who, with Pavlov, was the most famous and inﬂuential Russian, or, strictly, Byelorussian, psychologist of the twentieth century. His inﬂuence has also tended to increase in the last 25 years, even though he died in 1934. However, introducing him is notoriously difﬁcult, because there are a number of conﬂicting views about what his message was, as well as about what its merits were. This introduction outlines my interpretation of Vygotsky. A review of some other approaches to him is given in Chapter 8.