IN THE COURSE of several careers, James Bryant Conant set an extraordinary, and occasionally paradoxical, standard of public service. He stood at the center of several of the great public decisions of his times, yet he was only briefly a public official in any conventional sense. Along with others in the high priesthood of American science, he participated in the decisions to build and to use the atomic bomb. But, also like many of the others, he went on to warn the country against relying on nuclear weapons as the base of national power. He came to prominence first as the president of Harvard University, the very symbol of education for the intellectual and social elite. But he came an immensely effective advocate of that distinctively American institution, the comprehensive public high school.

This country's greatest schievement in social policy over the past half century is in our view, the public high school: a place where, for four crucial years, young Americans of widely differing backgrounds and interests work together under one roof. It is an enduring experiment in radical democracy, and it has become so widely accepted that it is difficult to imagine any other possibility. But, of course, Europe has always segregated its bright, university-bound students into special, more rigorous schools. That concept has occasionally been followed in big cities here, sometimes with very successful results. If you stop and think about recent history - particularly the panic over scientific education in the late 1950s - it is extraordinary that the idea of separate schools for the gifted was never more widely accepted. Part of the reason was Dr. Conant.

After he left Harvard in 1953, he went to Germany for four years, first as U.S. high commissioner, then as ambassador to the newly independent West German government. In early 1957 he resigned to return to the United States and undertake a massive examination of secondary education. The timing was fortunate; six months later the Soviets launched Sputnik and destroyed the comfortable American assumption that this country's technological superiority was beyond challenge. Suddenly a great deal of money and emotion was thrown into scientific training.

Like most other scientists, Dr. Conant had long before concluded that children could be taught far more rapidly than most high schools ever attempted. But, unlike some of his colleagues, he was also convinced that it could be done in schools that were teaching children at every level of ability. The atmosphere generated by Sputnik has long since dissipated, but the strongest of its reforms are still very much at work. A youngster at a very good public high school today is able to puruse subjects - calculus, organic chemistry, electromagnetic theory - that were left to the second and third years of the college curriculum a generation ago.

As Dr. Conant came to know American school system, he began to call attention to the flagrant disparities between the schools of the inner cities and those of the suburbs. As a good democrat, he was profoundly offended and use the words "social dynamite" in his book "Slums and Suburbs" in 1961. The phrase seemed a bit flamboyant at the time, but some of his readers recalled them four years later when the cycle of great urban riots began in Watts.

Dr. Conant, who died the other day at the age of 84, was not only a brilliant chemist and administrator. He was a wise man, who knew that a nation's political beliefs are reflected in the structure of its schools, and vice versa. He belongs to that long line of valuable Americans who have refused to concede any contradiction between intellectual excellence and education for democracy.