And it was. Arcadius seized the day, winning with the biggest, best effort of his life. The humans lined up, the horse was led in to the winner’s circle. Catching his breath now, he stood for the brief ceremony — a sweaty, dirty, hot, victorious athlete. It was as if he knew he had won. Arcadius stared regally to the distance, ears at attention, and everyone else paused, soaking in the victory. The cameras buzzed. Crowley jumped down, unbuckled the elastic girths, removed the leather saddle, breastplate, black and red cloth with the white 3 on it. The jockey folded it all up on his arm, patted his horse on the back, one more reward for the effort.

Two minutes later, Arcadius was dead — steps from the finish line he had crossed with so much power, so much life.

It was quick, shocking, certainly eerie. After walking from that winner’s circle celebration, while getting the usual after-race hosing and dousing with water, Arcadius stepped awkwardly to his right, raised his head, stiffened his front legs and dropped to the ground on his left side. Before he fell, his right eye went blank — flashing life, death, pain, something. Humans sprang to action — with more water, ice, medicine. It had looked like a heat stroke, even on a day when temperatures barely reached 70 under a gray sky. Horses do that: they overheat, they get medical attention, they cool off, they get up and walk away — tired, but alive.

Not this time.

Dr. Monty McInturff of the Tennessee Equine Hospital said it was an aneurysm, a heart attack. At first, the veterinarian heard a heartbeat — irregular, but there. Intravenous fluids went in. The people talked to the horse, calmed him, helped him, gave him every chance to recover. Arcadius quivered, raised his head once or twice, moved his feet, then went still. The ice bags came off, the fluids were disconnected.

The groom, Mike Benson, who had ridden eight hours in a horse van from South Carolina with Arcadius the day before, helped take off his horse’s bridle, and stood — shocked, gutted, alone, silent, as the race replay spun out on the infield television screen. A speck of mud dotted the corner of Benson’s eye, put there by his horse’s last few breaths. The owner, Ed Swyer, an Albany-area businessman who won two that day, could not speak. The trainer, Jonathan Sheppard, whose horses finished one-two-three in the race, walked away. Crowley came back for a trophy ceremony that did not happen, looked at his horse, retreated to the jockeys’ tent and asked a hundred mental questions.