question:  Why is the first part of the story so important?
context: It was exactly as he knew it would be: the milky-orange stream had become motionless and its minute whirlpools had stopped whirling; a nearby bee hung suspended over a paka plant, its transparent wings frozen in position for a downward stroke; and the heavy purple fluid overhead held fast in its manufacture of whorls and nimbi. With everything around him in a state of perfect tableau, Purnie hurried toward the ocean. So many times had he heard these thrilling tales that now, as he ran along, he could clearly picture the wonderland as though he were already there. He ran along feeling sorry for four-year-olds, and even for those who were only four and a half, for they were babies and wouldn't dare try slipping away to the ocean alone. Rather than spoil what was clearly going to be a perfect day, he chose to ignore the fact that he had been forbidden to use time-stopping as a convenience for journeying far from home. He chose to ignore the negative maxim that "small children who stop time without an adult being present, may not live to regret it." With it under his arm he bounded along a dozen more steps, then stopped abruptly in his tracks. The ocean lay at the ready, its stilled waves awaiting his command to resume their tidal sweep. Overhead, a flock of spora were frozen in a steep glide, preparatory to a beach landing. Further down the beach was a pair of two-legged animals poised in mid-step, facing the spot where Purnie now stood. Some distance behind them were eight more, each of whom were motionless in a curious pose of interrupted animation. When he got no reaction, he remembered that he himself was "dead" to the living world: he was still in a zone of time-stopping, on the inside looking out. It was time itself that Purnie had stopped, not the world around him. Sure, it's your money that put us here; it's your expedition all the way. "There is, there is.
output:  It shows the reader a skill that Purnie's been practicing
options:  It lets the reader know that it's Purnie's birthday (which becomes important later)  It lets the reader see how Purnie interacts with his family  It shows the reader a skill that Purnie's been practicing  It give great detail of the setting (which Purnie has to use later in the story to his advantage)