BEIJING — The mouth of the World's Fastest Man, flying along at a sprinter's clip and threatening to careen out of its lane, suddenly screeched to a complete halt. In mid-sentence, Usain Bolt looked at the clock on the wall, which read 10 minutes past midnight today, and stopped talking for an instant.

"Oh, I'm 22 now," the Jamaican birthday boy noted, then went right back into his riff on his own greatness, which no one in the room, or the entire world, could dispute.

"I blew my mind," he said, "and I blew the world's mind."

His own blown mind should cause no worries — it will be put back together with another night of prodigious sleep and perhaps some more Chicken McNuggets, his prerace meal of choice this week. But the world's mind may take some time to recover. Track and field, the Olympic Games and the sporting world at large witnessed something yesterday that cannot quickly be processed, for it involved the utter rewriting of the laws of human athletic possibility.

On a hot, steamy night that would have felt familiar in Kingston or the sugar cane fields of his native Trelawny, Bolt obliterated another world record, torching a world class field in the 200-meter dash in a time of 19.30 seconds, .02 of a second better than American Michael Johnson's 1996 record, which once seemed as untouchable as any in the entire sport. He finished more than half a second — an eternity in the realm of sprinting — ahead of the field.

On top of his record-breaking run of 9.69 seconds in the 100-meter dash on Saturday, it gave Bolt an unprecedented double: No sprinter had set world records in both the 100 and 200 in the same Olympics. Carl Lewis of the United States, at the 1984 Los Angeles Games, was the last runner who even managed to win both in the same Olympics.

"How fast can one human being go before there's no more going fast?" asked Kim Collins of St. Kitts and Nevis, who finished sixth in the race, expressing the stunned disbelief of those inside the sport at what they have seen from Bolt in the past week. "It's ridiculous. How fast can you go before the world records can't be broken?"

Unlike in Saturday's 100-meter final, when Bolt eased up with 20 meters to go, preening and prancing across the finish line, this time Bolt ran straight through it, never even looking around to check on his lead, which was enormous. Why the different approaches? Because he already owned the world record in the 100 before the Olympics, having run a 9.72 in May. But in the 200, his previous best still had been .35 of a second slower than Johnson's mark. "I saw I could get the record in the 200, so I told myself I wanted to leave everything on the track, and I did just that," Bolt said. "I told myself, 'If I'm going to get the world record, I must get it here.' "

On this night, Bolt was Secretariat, winning the Belmont Stakes by 31 lengths. He was young Jack Nicklaus, playing a game with which, to paraphrase Bobby Jones, the rest of his competitors were not familiar. He was Cassius Clay, shocking the world by stunning the champ and then bragging to everyone about it.

"I was looking at myself and saying, 'That guy's fast,' " Bolt said after watching a replay of his race, "I was saying, 'I look cool.' "

Bolt, 6 feet 5 with a giant stride, represents a new prototype in sprints, replacing the old one of 5-9 cannonballs with low centers of gravity. Bolt turns his legs over just as quickly, but eats up more ground with each stride.

"The stride — it's poetry in motion," said Renaldo Nehemiah, the former American hurdling champion. "He's not like a beast running. He's a gazelle. ... And he recognized the responsibility of seizing the moment, and he did it."

As recently as the 2004 Athens Olympics, the United States owned the sprints. But this year, Jamaica, a country with a population less than 1/100th that of the U.S., already has seen Bolt win a stunning double and its women sweep the 100-meter dash.