 Why is the first part of the story so important?
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. 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. "There is, there is. Now what do you suppose—" By now they had formed a widening circle around him, and he was hard put to think of an encore. The animals forming the circle stepped back and made way for two others who came through carrying a box.
 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)