The first is that individual development, including higher mental functioning, has its origins in social sources. This theme is best represented in Vygotsky's “genetic law of development”: “Any function of the child's cultural development appears on the stage twice, or on two planes, first the social, then the psychological, first between people as an intermental category, then within the child as an intramental category” (Vygotsky, 1931/1997, pp. 105–106).