Thirteen-year-old title character Sammy Clay and his estranged father, a vaudeville performer called "the Mighty Molecule," but born Alter Klayman near Minsk, are talking in a hammam in Brooklyn in the 1930s, reminiscing about Sammy's earlier bout with polio:
"You were so heavy to carry," his father said, "I thought you have to be dead. Only also you were so hot against the hand. The doctor came and we put ice on you and when you woke up you couldn't walk anymore. And then when you come back from the hospital I started taking you and I took you around, I carried you and I dragged you and I made you walk. Until your knees were scraped and bruised, I made you walk. Until you cried. First holding on to me, then on to the crutches, then not with crutches. All by yourself."
"Jeez," Sammy said. "I mean, huh. Mom never told me any of this."
"What a wonder."
"I honestly don't remember."
"God is merciful," the Molecule said drily; he didn't believe in God, as his son well knew. "You hated every minute. You just as good hated me."
"But Mom lied."
"I am shocked."
"She always told me you left when I was just a little baby."
"I did. But I came back. I am there when you come sick. Then I stay and teach you to help you walk."
"And then you left again."
The Molecule appeared to choose to ignore this observation. "That's why I try to walk you around so much now," he said. "To make your legs strong."
This possible second motive for their walks--after his father's inherent restlessness--had occurred to Sammy before. He was flattered, and believed his father, and in the potency of long walks. (106-107)