The death of Justice Potter Stewart at 70 is untimely in all but one respect. His admirable Supreme Court career inspires timely reflection upon the qualities that made him a superior judge.

For quite a while after President Eisenhower appointed Stewart to the court in 1958, he served as a kind of loyal opposition to the "Warren Court" majority. His frequent dissents made a literate and penetrating commentary on the judicial activism that was its trademark.

But Stewart, more a maverick than a mossback, found his center of gravity not in judicial naysaying but in a patrician individualism that was difficult to stereotype. Depending on the principle involved, he was often the ally of unexpected causes.

For instance, after his retirement from the court four years ago, Stewart confided to Fred Graham of CBS (the interview was to be sealed until his death) how he had urged the court in the mid-1960s to take a case testing the constitutionality of the Vietnam war and the draft. Had the court done so, it would have engaged in "activism" by anybody's standard, given the long tradition that the court treats great issues of war and peace as "political questions" beyond judicial scrutiny.

At that time of upheaval, there were known to be stray votes within the court for that excursion onto spongy turf. (The court will hear discretionary cases that at least four justices vote to hear.) William O. Douglas, for instance, advertised his sympathy with the anti-war protest; but then he was a liberal activist by inclination. That the urbane, discreet Potter Stewart stood also among the advocates of judicial intervention was not widely noticed at the time.

Yet it was Stewart's view that the war, never formally declared, violated an express constitutional command. "The Constitution," he told Graham, "clearly provides that only Congress can declare war. And Congress had never declared war." As for the draft, "here were people being unwillingly taken, under that law . . . for peacetime military training and service, and sent thousands of miles away . . . to be shot at and some of them killed."

Stewart knew as well as anyone the practical limits of judicial competence. He was, he often said, a lawyer, not a philosopher-king. It was therefore the more revealing that a justice such as Potter Stewart was willing to act. And that inclination points to the limited usefulness of facile formulas by which the judicial role is sometimes defined in theory.

It was primarily as a constitutional literalist that Stewart was speaking. But in a longer perspective, it was an outlook of familiar and honorable vintage. Though their views on other matters diverged, there was in Stewart's view on Vietnam an echo of his fellow Ohioan Robert A. Taft.

What Taft was saying with his usual directness in 1950 about the failure to declare war in Korea is all but indistinguishable from what constitutional critics -- older but now wiser -- were saying some 20 years later about Vietnam.

Taft's views disturbed "internationalist" opinion (they helped him lose the 1952 presidential nomination), but Taft was unsympathetic to the argument that changing circumstance had altered the stated limits of the presidential war power. So, apparently, was Stewart.

Stewart's advocacy failed; and might indeed have caused a destructive uproar had it succeeded and the court taken a Vietnam draft case and declared the war unconstitutional.

But it must have been quite an argument within the court. Among the justices of that period sat Abe Fortas, who had carried his role as a war counselor to Lyndon B. Johnson well beyond the usual limits of judicial discretion. How others divided we do not know.

But the story of Stewart's pursuit of an old maxim ("let justice be done, though the heavens fall") suggests that the qualities of the superior judge are ultimately inseparable from qualities of mind and character. Invoke jurisprudential theory as one will, it leads only to the threshold of understanding how a superior judge views his duties -- and not far beyond.