Johnson used steroids surreptitiously and in defiance of clear rules that are constantly reiterated. However, Johnson and many others involved in the intense pursuit of competitive edge may not really understand the reasons for the rules he broke.

When judging a performance-enhancing technique or technology, the crucial criterion is: Does it improve performance without devaluing it. Begin by considering precisely the value drained away by cheating, then decide if use of steroids constitutes cheating.

Bartlett Giamatti, baseball's next commissioner, is the designated metaphysician of American sport. Last year, he flexed his mental muscles regarding disciplinary action against a pitcher who was caught using sandpaper to scuff balls, thereby giving pitches more pronounced movements.

Giamatti noted that most disciplinary cases involve impulsive violence, which is less morally grave than cheating.

Such acts of violence, although intolerable, spring from the nature of physical contests between aggressive competitors. Such violence is a reprehensible extension of the physical exertion that is integral to the contest. Rules try to contain, not expunge, violent effort.

But cheating derives not from excessive, impulsive zeal in the heat of competition. Rather it is a cold, covert attempt to alter conditions of competition. Toward cheating, the proper policy is zero tolerance.

Intensity in training should be rewarded with success in competition. But intense training should involve enhancing one's powers by methods (e.g., weight training) or materials (eat your spinach) that enhance the body's normal functioning.

It is one thing to take vitamins, another thing to take a drug that facilitates abnormal growth (or makes a competitor abnormally aggressive).

An athlete steps over the line separating legitimate from illegitimate preparation for competition when he seeks advantage from radical intrusions into his body.

A radical intrusion is one that does not enhance normal functioning but rather causes the body to behave abnormally. Illegitimate interventions cause an athlete to perform not unusually well - every athlete's aim - but unnaturally well.

Steroids are dangerous to the user's health. Even if an athlete is willing to run the risk, his competitors should not have to run it in order to compete.

That is a sufficient reason for proscribing them. But even if steroids and other performance-enhancing drugs were risk-free, there would still be sufficient reasons for cleansing sport of them.

Drugs that make sport exotic make it less exemplary. Sport becomes less of a shared activity. It becomes less a drama of people performing well than a spectacle of bodies chemically propelled.

Athletes who seek a competitive edge through chemical advantage do not just overvalue winning; they misunderstand why winning is properly valued.

It is properly valued as the reward for, and evidence of, praiseworthy attributes. They include the lonely submission to an exacting training regimen, and the mental mastery of pressure, pain and exhaustion.

In short, sport is valued not only because it builds character but because it puts on display, and crowns with glory, for the elevation of spectators as well as participants, attributes we associate with good character. Good character, not good chemistry.