What role does mediation play in culture?

In view of development, It is important language role by Vygotsky. It is mediate between culture and human. In developmental psychology, Piaget's theory is very important. He was affected to child cognitive development theory. But, other theorist start to criticized Piaget's theory. Vygotsky is same person who criticized Piaget's theory. He insisted that the context is important to children. Especially, language was moved in mediation play. It is social-cultural approach. There is language(context, culture), there is human too. This is can be conversely.