Breaking the last taboo, she cocks a snook at Ernest Hemingway, who celebrated this Spanish rite as the quintessence of a man's destiny to confront and overcome his fear of death. The extent of Sanchez's achievement - the bullfighting equivalent of taking silk or being awarded a doctorate - may be judged by the fact that even for a man, becoming a matador is an almost unrealisable dream. In the words of the greatest matador of all, Dominguin, who died earlier this month, for every 10,000 who try, only one makes it.
There have long been female bullfighters, but only four other women since the 1930s have earned the right to graduate from fighting young novillos to facing the older, bigger and much more dangerous adult toros. The first, and most famous, was Juanita Cruz, born in Madrid in 1917, who fought as a novice in the 1930s. But Francisco Franco banned female matadors from fighting on Spanish soil after he came to power in 1939 - though he did allow women to become rejoneadores, bullfighters on horseback - so she qualified and made her career in South America.
The others were the Colombian Bertha Trujillo, who qualified in 1968 and became an instructor in Cali bullfighting school, and the Mexican Raquel Martinez, who married an American policeman and has a son who wants to be a bullfighter. The only other Spaniard is Maribel Atienzar. Born in Albacete in 1959, she originally wanted to be a nun, but she too qualified in South America.
Sanchez's achievement is also a victory for Spanish feminism. Forget women space navigators, if a woman can become a matador, there is nothing she cannot do. It is all the more remarkable considering that the Spanish feminist movement is only 20 years old. Until Franco died in 1975, a woman in Spain could not even open her own bank account, or travel any distance without her husband's permission. Juridically, she was a man's property.
In January 1976, 2,000 women demonstrated for the first time, under a banner saying "Women! Fight for your liberation". As they marched down Goya Street in Madrid's most conservative area, some passers-by shouted "Putas!" (whores!), but many of the men applauded them as they went past. The demonstrators must have known, and many of the men watching them may have guessed, that they were heading for a police baton charge.
There is nothing more likely to arouse admiration from a Spanish man than a display of courage. Hemingway was right about this. Women's achievements over the past 20 years in Spain probably owe more to winning men's respect for their bravery than appealing to their sense of solidarity.
The divided reaction on Goya Street 20 years ago is a fair summary of that dished out to Sanchez. Andit matches the male response to any Spanish woman who has fought to throw off the subjugation of 20 years ago.
Today, the new Spanish conservative government has four female ministers, one more than its Socialist predecessor. Also, the head of the Spanish state broadcasting company, the equivalent of John Birt, is a cool and competent woman of 33.
Many in the bullfighting world are furious at Sanchez's achievement, regarding a female bullfighter as simply a contradiction in terms. Jesulin de Ubrique, one of the current crop of strutting bullfighting superstars, says he will not appear on the same bill as Sanchez. This from the man who mounts special performances for women-only audiences.
Another prominent bullfighter, Joselito, once said he was totally opposed to women entering the ring "because a woman is subtle and the bull is crude". Anyway, he added, a man when he faces the bull faces death and has to be on top form. How could a woman face a bull if she were having her period? All the greater cause for admiration, one might think.
The bullfighting spectacle - one doesn't say "sport" here, where corridas are reported on the culture pages of the newspapers - has a profoundly sexual impact, and this is conventionally appropriated as a male sexuality. The sight of a young, tightly clad and besequinned person conducting themselves with elegance and bravery in the face of death exerts an erotic grip upon enthusiasts.
Gerald Brennan observed this in his classic South from Granada: "A mysterious change comes over Spaniards in the presence of death ... as if their own death instincts had been unloosed and given vicarious satisfaction. It is not sadism or love of cruelty, but a sort of fascinated absorption of what they regarded as the culminating moment of existence. They unite themselves to it, as the voyeur may do to the spectacle of another person's orgasm."
Among the many theories of what the bullfight symbolises is one in which the matador enters the ring in the role of the woman, flirting with the bull, distracting it, confusing it with his dazzling appearance and not a little cruelty. Then, the theory goes, when the bull is befuddled and subdued, the fighter assumes the man's role, exerts his powers of domination, absorbs the once-dominant qualities of the victim to conquer the fear of death by the final sword thrust, the penetration. How, the purists protest, could a woman do this?
The proof, they say, lies in the fact that Sanchez, however accomplished, does not kill well. Only a man has the killer instinct.
None the less, Sanchez is now treated seriously, which in Spain is to say that they treat her as if she were a man. But there are still lapses. Yesterday a radio interviewer asked her if she expected to marry a bullfighter. At which she paused, then answered icily that she had no idea.
Her bulges may be ill-distributed for a bullfighter - as one journalist crassly remarked some years ago - but she has cojones, and in Spain having balls is what counts.