Out West there is Zenyatta. When you first stand next to her, it's with a mixture of awe and fear. There are tall horses, and there are powerfully built horses, but rarely do the radical fringes of those characteristics converge in the same animal. There she towers, and yeah, that's the Zenyatta you've seen run over everybody in the stretch in all 12 of her races. Win number 12, victory by a head in the Aug. 9 Clement Hirsch, produced more derision than exultation. Has it been pointed out that Zenyatta ran her final quarter-mile in less than 23 seconds that day? That she averaged sub-12-second furlongs for her final half-mile? Possibly no other horse in world could have won that race the same way. Zenyatta may be the best horse in the world. Back East there is Rachel. Three-year-old fillies do not beat older males in summertime dirt route races. No 3-year-old filly had won the Woodward Stakes until last month. Rachel Alexandra dueled through a 22.85-second opening quarter-mile in the 1 1/8-mile Woodward. They should have been scraping her off the track with a spatula. Instead, she turned back one of the best older dirt horse in the country, Macho Again, with a final eighth of a mile in less than 13 seconds - and she galloped out around the turn all by her lonesome, after Macho Again had shut it down. Rachel Alexandra could be the best horse in the world. In Ireland resides Sea the Stars. That was a clever name. The colt is by Urban Sea, and a half-brother to the mighty Galileo. You should see him run. Sea the Stars has won seven straight since finishing fourth in his career debut. In 2009, no horse has got within a length of him in five of Europe's most important races. "I suppose he seems to be the whole package, if you like," trainer John Oxx said. "He has these terrific looks. He's big and strong with these great limbs. He was always an outstanding individual with great promise. He had that sort of presence about him. From the time we broke him he always stood out - a class apart from everything." Yep. Sounds like the best horse in the world. But let us not forget France's Goldikova. If the competition is for radiance at rest, Goldikova couldn't warm up Sea the Stars or Zenyatta or even Rachel. The filly is smaller, less flashy. Until she runs. If you blinked at the wrong midstretch moment of the 2008 Breeders' Cup Mile, you missed Goldi going from a boxed-in fourth to a home-free first. In August, she won a legit French Group 1 by six lengths. Six lengths! So, come on people, who is (drum-roll, please) the best horse in the world? That is a little like asking who is the best boxer in the world or the best baseball player in the world. Yeah, the 250-pound guy batters the 150-pounder, but does that make him a better boxer? Is one home run worth two great defensive plays? "This is a very difficult exercise trying to compare males and females, turf and dirt, and from different parts of the world," Bill Nader said in an e-mail. Nader has been involved in racing in different parts of the world as a former senior vice president with the New York Racing Association and now executive director of racing for the Hong Kong Jockey Club. "It is a lot like trying to compare Bird and Magic or Mantle and Mays, though more difficult because of the distance and surfaces." It's not like we'll line these animals up at a neutral site and distance and see who comes out on top. Rachel apparently is done for the year. If the Paris turf stays dry as forecast, Sea the Stars may start only in the Prix de l'Arc d'Triomphe over 12 furlongs Sunday before calling it a career. That would be the end of a possible Zenyatta-Sea the Stars matchup in the 10-furlong, synthetic-track BC Classic at the Oak Tree meeting at Santa Anita. If things go as planned, Goldikova will be doing her BC Mile thing after starting Saturday in the seven-furlong Prix de la Foret at Longchamp. "It's not just comparing apples and oranges, but apples and giraffes," said Daily Racing Form publisher Steve Crist. "I think Rachel Alexandra is the best or most accomplished dirt horse in the world right now, but how do you compare a nine-furlong dirt horse and a 10-furlong grass horse? You don't." But the whole act of horse-playing rests upon developing an opinion, so how could a horseplayer not have one on such an epic subject as the best horse in the world? And when people want to back up their opinion, they often go to the numbers. In North America, we try to classify using time, evaluating talent by speed figures. "When you go through the DRF chart book and look at the list of the top performances of the year from a speed-figure standpoint, there's a pretty good correlation with a common-sense analysis of who the best horses are," said Andrew Beyer, whose Beyer Speed Figures are used in the Daily Racing Form past performances - and supplied to voters to help them decide year-end Eclipse Awards. "The best speed figure in the country this year belongs to Rachel Alexandra." Rachel's top Beyer figure is 116. That falls short of Beyer's threshold for greatness, which he put at 120, though Beyer said he would "call her great." Ghostzapper has earned the highest Beyer, a 128. Zenyatta, with a 104 top in 2009, barely gets into the Beyer conversation. Speed figures can work in the U.S. because of the uniformity in racing. Everyone runs the same direction on flat ground over surfaces that - until the recent advent of synthetics - could easily be lumped together. Also, Beyer said, "Horses pretty much run hard all the way, so the final time measures how good they are." But check your Beyers at the airport before you travel across the Atlantic. Overseas, numbers are brewed with a different recipe. Without racing secretaries in Europe, official handicappers, either national or local, are tasked with fitting horses into their proper competition levels through the assignment of a numerical rating. A horse rated 80 could run at the high end of a 60-80 handicap race while carrying top weight, or it could run in an 80-100 handicap race and carry low weight, explained Ciaran Kennelly, currently an international racing consultant but for 12 years the senior Irish handicapper. Every horse in a country will have a rating after racing three times. "By three times running, it gives the national handicapper, hopefully, a reasonable guide to make an assessment based on the opposition," Kennelly said. The opposition is judged by link, or master, horses. Unrated Horse A raced against Horses B, C, and D, which have established form and an accompanying rating from which Horse A's can be derived. In 1977, recognized ratings systems encompassed only England, Ireland, and France, but Italy and Germany soon came in, America and Japan later, and now all countries with anything like major races are swept into international rankings. "Over the years, through horses running in Australia and Hong Kong, the Japan Cup, Singapore, Dubai, the Breeders' Cup, that is the way we can see competition from several different continents, different countries, and that helps to get a guide on a level of racing," Kennelly said. "By and large I think it works out quite well." Well enough that the International Federation of Horseracing Authorities created the World Thoroughbred Rankings in 2004 - the official list of the best horses in the world. The body has 14 voting members who meet in July and September and again at year's end in Hong Kong to assess the form of every horse in the world who has run well enough to merit an international rating. "It's not an easy process, because even within a region, it's hard to get a really solid line on the differences, to get a handle on the relativities, to keep track of all the form on all the horses," said Nigel Gray, who is co-chair of the WTR committee, and head of handicapping and race planning in Hong Kong. "When you're assessing racehorses you never cease to be surprised, but if the Thoroughbred were not really a consistent animal, this process could not be conducted," Gray said. In the September 2009 rankings, Sea the Stars was weighted at 135, the highest ranking since the WTR started putting out their numbers. Rachel Alexandra? She checks in down at 125 along with Conduit, Mastercraftsman, and Zenyatta. A ranking is attached to a single race but is supposed to reflect the horse's overall quality. Most ratings systems, including the WTR, identify the distance range and surface on which a rating was achieved. The process can produce questionable results. The WTR September list had Gladiatorus weighted at 126, fifth best in the world. That rating was achieved in the Dubai Duty Free, in which Gladiatorus ran like a crazy horse and won by more than three lengths. But Gladiatorus had never run that well before last winter, and in three subsequent European starts, he has been defeated by a combined 45 lengths. The Timeform global rankings from England don't name Gladiatorus in the most recently published list, which includes 34 horses. Timeform and Racing Post, a competitor whose ratings are used in Daily Racing Form past performances for overseas horses, are commercial rather than national ratings services and can perform more gyrations before arriving at that final master number. For instance, Timeform equals time plus form, and this service roughly approximates what speed-figure makers in the U.S. do, establishing par times for different levels of races at specific tracks. The lack of fractional times in European racing surely complicates the task considerably, but Timeform claims to have reliable pars established for every track in Ireland and England, and most in France, according to spokesman Kieran Packman. Their database also includes U.S. racetracks, but Packman said rating an American horse like Rachel Alexandra (129 Timeform) was a much dicier proposition than figuring out a Sea the Stars (140). "We'd be the first to hold our hands up in terms of a filly like Rachel Alexandra," Packman said. "It's absolutely not as robust as the horses we're rating in Europe." The Kennellys and Grays who work for non-commercial ratings entities must take a diplomatic approach in answering the question of who is the best horse in the world. The Timeforms can wax more enthusiastic. Sea the Stars's Timeform rating of 140 puts him at the same level as Dancing Brave, Dubai Millennium, and Shergar. Only four horses, Mill Reef (141), Brigadier Gerard and Tudor Minstrel (144), and Sea-Bird (145) have been rated higher. "As far as we're concerned, (Sea the Stars) already sits in the top 10 all time," Packman said. "We've been massively impressed. I've been fortunate enough to see him, and all pieces of form this year just lead back to him." But Sea the Stars didn't actually run a 140 Timeform winning the Irish Champion by more than two lengths over Fame and Glory on Sept. 5 at Leopardstown, at least not the way Rachel ran a 116 Beyer winning the Haskell Invitational on Aug. 2 at Monmouth Park. "Visually, we took the subjective view that if he had been pressed by a superior horse, he could have run faster," Packman said. Subjectivity must be ruled by what we best understand. In other words, European-style ratings systems may have an inherent tilt toward European horses. Curlin might have been top-rated in 2008, but he first got that 130 rating by running in Dubai against an international field. And if you wanted to bring subjectivity in, Rachel Alexandra's numbers from the Woodward aren't much guide at all. Her Beyer couldn't account for the crushing early pace that should have got her beat. And the international ratings were lowered because of the weight break she got from Macho Again and the fact that Macho Again has no major international ranking. Would a tuned-in U.S. racing observer contend that Well Armed, somewhat highly rated because of Dubai World Cup win, was a much better dirt horse than Macho Again? Nader, the former New Yorker in Hong Kong, can see both sides. "I am somewhere in the middle because I recognize that top females beating top males on dirt is a demanding task at classic distances, and this is a distinction that has to be made when comparing racing conducted on dirt as opposed to turf," he said. "[Rachel Alexandra] is very impressive and should be ranked higher in my view." Without figures or ratings as a guide, we are getting back to Crist's apples and giraffes. What makes one great horse greater than another great horse? Some would say consistency. "They've got to have the mental makeup to go with the circumstances," said Steve Asmussen, Rachel Alexandra's trainer since early May. "There are amounts of pressure that cannot be absorbed by anything that isn't great. Not only being able to do it, but being able to do it under those circumstances repeatedly, to know it's not easy, and still to go do it. You got to be tremendous physically, but you've got to be even tougher mentally." Points for Rachel. But also valued is the ability to do different things exceptionally. Sea the Stars has won at distances from one mile to 1 1/2 miles in 2009 and over courses straight, left-handed, and right-handed. And then there are the standout specialists, like Goldikova on a fast-turf mile. Liz Price of Paris-Turf cited Yeats's four straight wins in the Ascot Gold Cup as reason enough to be ranked. Crist listed Fabulous Strike: As the best dirt sprinter in the world, the horse should be considered one of the best horses in the world. "The only fair way to do this, I think, is to concede to each horse his, her own context," Gary West of the Fort Worth Star-Telegram said in an e-mail, explaining why he had ranked Rachel over Sea the Stars. "And doing that puts Rachel Alexandra at the top, which is to say she stands even further above the crowd than he." Rachel, West contends, "might be the best filly to come along in 64 years," but West said he "can't imagine any European putting Rachel on top." No, not when Sea the Stars has them in thrall. His trainer, Oxx, is 59, and saw in person several of the most highly regarded Europeans in the last 50 years. Mill Reef was "a smashing little horse," Oxx said, but his lack of size might have slightly lowered his ceiling. Nijinsky "had more of an aura about him." But Nijinsky, Oxx said, "was a little temperamental, and it cost him in the end. He lost his last two races." Sea the Stars is neither hot-blooded nor slightly small, and even on wet turf that he does not especially favor, he can win. If Sea the Stars aces the Arc, or belittles Breeders' Cup Classic rivals, his name will get tossed around as one of the all-time greats. And in 2009, that surely would be enough to make him the best horse in the world. Unless you happen to feel otherwise.