Play is an interference phenomenon. Two children playing together create a balanced binary opposition. Three children is a more fluid, but also more dynamic, harmony. Four children polarize again in two doubled units, more stable than the triangle. Five is again fluid; six is normally the largest number of children that can play an improvised game that isn't organized by a dominant leader among them. Only once had Kaspar seen seven children play together in a fair and balanced way. That had been artists' children who had traveled with the circus a whole summer; it had been at the end of the season, they had known they would be leaving each other, and it had lasted less than an hour. Games for more than seven children required rules set and supervised by adults, like ball games, for example.
There were no adults in the scene before him, no dominant sound. There were eleven children. And they played in perfect harmony.
...
The Quiet Girl, Peter Høeg.
