What is the meaning behind this quote? Chapter.4 page 62 Lord of the Flies-William Goldin

“Roger stooped, picked up a stone, aimed, and threw it at Henry — threw it to miss. The stone, that token of preposterous time, bounded five yards to Henry's right and fell in the water. Roger gathered a hand

handful of stones and began to throw them. Yet there was a space round Henry, perhaps six yards in diameter, into which he dare not throw. Here, invisible yet strong, was the taboo of the old life. Round the squatting child was the protection of parents and school and policemen and the law.” (Chapter 4 pg. 62) Lord of the Flies-William Goldin