From the clearheaded conviction he displayed throughout his trial and imprisonment to the calm, defiant way he went to his death, Timothy J. McVeigh exhibited the determination and demeanor of a true idealist, which is, of course, precisely what he was.

That may be a jarring thought, but it is hardly arguable. And it holds an important lesson for all who claim to care about the meaning of good and evil.

The lesson was recounted in another context by the late celebrated biologist/essayist Lewis Thomas, who recalled the legendary dedication of an antecedent of his, a medical doctor who lived in the 1800s. The talented and humanitarian gentleman would selflessly make the rounds of a tuberculosis hospital every day, visiting the patients, placing his bare fingers into their throats to examine their tracheae, moving from patient to patient - without once ever thinking to wash his hands.

In those days before Lister and sterilization, much spread of disease was likely due to such well-meaning devotion to the cause of medicine. The idealism and good intentions were there. What was missing was only knowledge, but that made all the difference.

The doctor, needless to say, was in no way morally responsible for the damage he wrought. He had no way of knowing what his well-intentioned actions were yielding. But he stands as a poignant example of the fact that idealism doesn't necessarily lead to good results.

And it need not even be associated with goodness at all. The Talmud tells of a renegade Cohein Gadol, or High Priest, in the Second Temple era, who confessed to a friend that he had performed the most important priestly service of the Jewish year, the offering of incense in the Holy of Holies on Yom Kippur, in the manner favored by the Sadducee sect, against the dictates of Jewish religious law. The friend asked him if he was not afraid of being discovered by the other priests. "All my life," he responded, he had been "pained by the verse" that he understood in the Sadducee manner. "And I wondered," the renegade continued, "when the opportunity [to fulfill it] might come before me. Now that it has, shall I not fulfill it?"

What is striking about that Talmudic passage is that it is, practically verbatim, what another account, in a different Talmudic tractate, has Rabbi Akiva saying as he was taken by Roman officers to his execution for having violated an imperial edict against teaching Torah. As he recited the Shma, his students were incredulous at his presence of mind while facing the iron combs with which the Romans flayed him alive.

"All my life," the sainted Jewish sage replied, addressing their wonderment, "I was pained by the phrase "[and you shall love Hashem your God] with all your soul'" in Shma, which implies that we must be ready to give up our very lives for the glory of heaven if necessary. "And I wondered when the opportunity might come before me. Now that it has, shall I not fulfill it?"

The implication of the identical wording is inescapable. The editors of the Talmud were subtly teaching us that the Sadducee's conviction was every bit as sincere as Rabbi Akiva's. The Sadducee was an idealist. But he was wrong. And that made all the difference.

Hitler and Stalin were idealists too, and as they faced death they no doubt regarded their lives as having been lived in dedication to a higher cause, to the betterment of mankind, no less.

Yassir Arafat may even be an idealist too, though there are ample grounds for wondering whether his motivations might include less than rarified concerns. The "martyrs" of Islamic Jihad and Hamas, though, are certainly idealists. Though they may be focused hungrily on the particular pleasures of the Islamic afterlife, they clearly die convinced that they are holy men dedicated to a sublime cause.

But they were, all of them, dead wrong. And, again, that makes all the difference.

Timothy McVeigh surely took great pride in his idealism and in the "unconquerable soul" he assigned himself. But he, too, was wrong. Indeed, like so many idealists, he was evil.

And so, as our image of him recedes into the dark, putrid place where bad memories reside, we might consider redeeming his life in a tiny way by reflecting on the lesson he inadvertently taught us, a lesson of particular poignancy for our relentlessly relativistic times: it's not enough to be an idealist; one must be right and good or our idealism means nothing at all.

Rabbi Avi Shafran serves as director of public affairs for Agudath Israel of America.