(c) Lev Semyonovich Vygotsky was a Soviet psychologist, the founder of a theory of human cultural and bio-social development commonly referred to as cultural-historical psychology, and leader of the Vygotsky Circle. Vygotsky believed children's thinking is affected by their knowledge of the social community (which is learnt from either technical or psychological cultural tools)and culture. He also suggested that language is the most important tool for gaining this social knowledge; the child can be taught this from other people via language.