On Dec. 15, 2007, I sent a friend an e-mail with a YouTube link to an ordinary allowance race that had taken place earlier that day at Hollywood Park.

"Check this girl out," the e-mail reads. "3YO half to Balance, by Street Cry, and is she huge! Now 2-for-2 lifetime and check out that late kick. Keep an eye out. Could be something."

Three years, 18 races, over $7.3 million and countless hearts stolen later, Zenyatta is no longer just Balance's little sister. She's indeed something.

It's been just over a month since Zenyatta's trademark heart-stopping rally came up just a head short - for the first and only time in her career - in the Breeders' Cup Classic. Last night, the big mare arrived home in Kentucky for good. After her emotional farewell ceremony at Hollywood Park on Sunday, she flew into Lexington Monday night, made a brief appearance at Keeneland, across the road, and then took a short van ride to Lane's End Farm. She'll be bred next spring to a stallion not yet disclosed.

Historians will debate Zenyatta's place in history forever. How many Grade I winners did she defeat? Will she be regarded as the best horse of California's synthetics era? Did any other highly-lauded racehorses ship as infrequently as she did? Why didn't she face males more often? Does she or does she not finally deserve Horse of the Year?

But in the end, Zenyatta is worth more than the sum total of all her parts - as witnessed at this year's Breeders' Cup.

I have never been in a racetrack crowd that was as alive, and as united behind one horse, as I experienced at this year's event at Churchill Downs. There were the guys who flew in from California in the purple '19' jerseys and the pink-and-teal shoelaces. There were the little girls in pink-and-teal dresses clutching Beanie Babies with Zenyatta saddlecloths. There was the gaggle of middle-aged women with brown felt horse ears attached to their caps, with cotton balls stuffed in them. It felt like stepping back in time, to an era before off-track wagering and the rise of other sports, when racing was the sports of kings and these horses were household names, heroes.

When the horses stepped onto the track for the Classic walkover, that crowd - waiting all day - started up a roar that sustained itself for the next half-hour, culminating in a frenzy as Zenyatta, who appeared hopelessly beaten leaving the backstretch, suddenly swung to the outside, taking dead aim on the leaders at the head of the stretch. Standing there as the entire grandstand shook in support of one incredible horse was an out-of-body experience. And although we all know that rally fell just short - in the end, Zenyatta's will to try even while facing the prospect of defeat, a situation that might have cowed many other horses, defined her.

As she walked past us on the clubhouse turn, on her way back to the barn for the final time in her career, I looked down the rail. There was hardly a dry eye visible. Everyone was still on their feet, applauding her as a conquering hero, calling out praise to her - "Thank you" and "We still love you." I suddenly remembered visiting Secretariat's grave two days earlier, thinking of what he meant to so many people, and the knowledge that great horses like this are a once-in-a-lifetime gift.

And I suddenly found tears on my own face, and my throat closing up as I tried to call "Thank you, Zenyatta" as she walked away into the darkness. Thinking of what she meant to so many, and how much I will miss her - miss that trademark strut to the post, the unfathomable charisma, the feeling of my heart in my throat as she rallied. It was a moment I never would have envisioned when I wrote that short e-mail about Balance's little sister three years ago.

Most racing fans would count themselves lucky to see one true superstar. I've been blessed with the gift of more than one. Cigar was my first true love, and then I waited nearly a decade until Zenyatta and then Rachel Alexandra came along. Zenyatta's retirement to Lane's End - just a short drive from Stonestreet, where Rachel now resides - officially closes the book on the story of these two amazing girls, and the wild ride they took the racing world on. It's been quite a chapter.

I think I've gotten my quota of great horses for my lifetime. But rather than feeling sadness as we bid farewell - it's time to be thankful for what we had, and start looking for the next one.

You know you likely never will. But that's why we love the game - for the possibility.