 Why is the first part of the story so important?
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. 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." 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. 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. "There is, there is.
 It shows the reader a skill that Purnie's been practicing
 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)