Love of play is the most obvious distinguishing mark of young animals, whether human or otherwise. In human children, this is accompanied by an inexhaustible pleasure in pretence. Play and pretence are a vital need of childhood, for which opportunity must be provided if the child is to be happy and healthy, quite independently of any further utility in these activities.
Source: On Education, especially in early childhood, 1926, Pt. 2： Education of character, chap. 5: Play and fancy
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