Huizinga, J. (1971). Homo Ludens: A Study of the Play-Element in Culture (1st ed.). Beacon Press.
Homo Ludens is a book originally published in Dutch in 1938 by Dutch historian and cultural theorist Johan Huizinga. It discusses the importance of the play element of culture and society. Huizinga suggests that play is primary to and a necessary (though not sufficient) condition of the generation of culture. The Latin word ludens is the present active participle of the verb ludere, which itself is cognate with the noun ludus. Ludus has no direct equivalent in English, as it simultaneously refers to sport, play, school, and practice.
p. 10 - Magic Circle
"All play moves and has its being within a play-ground marked off beforehand either materially or ideally, deliberately or as a matter of course. Just as there is no formal difference between play and ritual, so the 'consecrated spot' cannot be formally distinguished from the play-ground. The arena, the card-table, the magic circle, the temple, the stage, the screen, the tennis court, the court of justice, etc, are all in form and function play-grounds, i.e. forbidden spots, isolated, hedged round, hallowed, within which special rules obtain. All are temporary worlds within the ordinary world, dedicated to the performance of an act apart."
The concept of the magic circle is one that is necessarily abstract. However, it's a useful lens to have in your toolkit. The "magic circle" in this ...