Nineteenth-century children's literature came into its own with its captivating scenes of play that serve as humour, invoke nostalgia in the reader, enable moral lessons, and enrich and complicate the personalities of the child protagonists. Play in animals has long puzzled researchers, seeming to be a useless activity that expends energy and risks physical injury. Russian developmental psychologist Lev Vygotsky particularly viewed play socioculturally, believing it to be empowering for children and emphasizing its symbolic function. Modern theorists build upon these established notions of play as developmentally crucial and socially empowering, even symbolically transformative of real space, time, objects, and intention. Children have long preferred to make their own rules and break them at their leisure, and they avidly defend their own play spaces. This chapter also presents an overview of the key concepts of the book.