Biles smiled nearly the whole way through her floor exercise on both days of nationals, as if she were dancing barefoot on the lawn of her backyard, with no one watching. While waiting for her turn on the vault, she started laughing just seconds before sprinting down the runway. That’s just before she landed one of the world’s hardest vaults — an Amanar, which has one flip and two and a half twists. Judges awarded her effort with a nearly flawless 9.9 for execution. Biles’s control and execution are just so crisp that her competition can’t keep up.

Raisman, who was in her rotation group, watched and marveled at the ease with which Biles floated from event to event while Raisman and the other gymnasts fought to stay focused. Both train about 30 to 34 hours a week, but with much different attitudes.

“I could never be as relaxed as she is, never,” Raisman said before explaining that her coach, Mihai Brestyan, had warned her not to let Biles’s loosey-goosey attitude rub off on her. “Mihai said when you can vault like Simone, then you can relax. Until then, you just focus.”

For Biles, the sport may just be simpler for her than for anyone else. She was made for gymnastics, with a tiny yet powerful body that makes it easier for her to launch herself into the air and twist and flip. She also has an uncanny ability to understand where her body is in the air in relation to the ground, an awareness that was noticed by her coach, Aimee Boorman, soon after she started taking lessons as a young child. Biles is 4 feet 9 inches and so springy that she might have springs for joints, although that suspicion remains unproven.

The Karolyis said that the last time they had seen someone as naturally gifted as Biles was 40 years ago, when they coached Nadia Comaneci, the Romanian gymnast who won an Olympic gold medal in 1976 and scored the first perfect 10 at a Games.

Comaneci was not bubbly the way Biles is, though. Far from it. When she performed her routines, she looked like a somber scientist following the steps of an equation, so careful not to misstep. She was great at what she did, but it looked like work.

“Nadia kept everything inside,” Bela Karolyi said. “You had to guess what she was feeling.”

You don’t have to guess what Biles is feeling. Her grins and giggles say it all.