In the judgment of a longtime participant in government at various levels, President Carter has undertaken a task more formidable than that of any man who has ever held the office. He is proposing to bring under control the revolution worked by the motor car, the jet plane and all the devices that have rested on fossil fuels. He is jarring awake the American people who for decades have depended on the private motor car.

What is more extraordinary is that he needn't have done this. Short of some upheaval such as another Middle East oil embargo, he could, in all probability, have drifted through a first term and perhaps even a second four years.

Both Presidents Nixon and Ford warned of the perils of the energy crisis. But they did nothing about it beyond rhetoric. Once the immediate impact of the embargo of 1973, with long lines at the gasoline pumps, was over, the old ways were back. Sure, we could go on forever, with 6 per cent of the world's population using 30 per cent of its resources.

So Jimmy Carter has jumped into the fire of a fierce controversy. Other Presidents have endured fearful torments. Lincoln hoped to save the union without a war but after the Confederate firing on Fort Sumter, whatever hopes he still cherished were gone. Pearl Harbor opened the way to the war Franklin Roosevelt had sought against the Fascist powers, and when Hitler made one of the gravest errors of his mad career by declaring war against the United States, the President was given a go-ahead to save Britain and drive the Nazis out of Western Europe.

In his encyclopedic and yet fascinating book "The Glorious Burden," Stefan Lorant shows the Presidents from Washington through Ford and up to Carter enduring the torments of the office. Their course was shaped by events over which, in the crunch, they had little or no control.

Almost completely unknown two years ago, the peanut farmer from south Georgia has chosen a course that is rough and uphill most of the way. Will he succeed in changing the habits of millions of Americans who have gone on for decades in their own private, individualistic ways?

It is too early to say. There will certainly be delays in Congress, and these delays may ultimately deaden the impact of the program so that its thrust will be lost in a welter of dispute. One weakness, it seems to me, was to rely in the first phase on voluntary conservation. The President might have called for an immediate increase in the gas tax, therefore forcing a quick showdown with Congress. This could also have meant a quick and perhaps fatal setback if Congress said no.

Opinion both on Capitol Hill and in the country has it that the gas tax has little or no chance of passage. There are even those who believe it was put in by Carter as a bargaining chip to be abandoned as he discarded the $50 tax rebate. Nothing in his record shows any reluctance to throw overboard whatever may seem to be inconvenient or self-defeating.

Given the equalization process in the cost of crude oil, as called for in the Carter program, the price of gas at the pump is sure to go up regardless of what happens to the tax. Price as a deterrent is open to serious doubt. A colleague just returned from Italy reports that with gasoline at $2.40 a gallon, city streets are as jammed with traffic as ever and the freeways are buzzing with motorists going 90 miles an hour.

One may argue that the Italians, given their record on income tax collection, are an anarchic people. But it is well to look at our own record before making any optimistic predictions about the success of conservation through car pooling and public transportation.

With the whole world watching, it will be a test of our self-discipline and our capacity to respond as a nation to what is unquestionably a great crisis that can mean so much for the future of our children and grandchildren. In his television address Carter called it the moral equivalent of war.

This was the title of a book by the distinguished American philosopher William James, published not long before his death in 1910. As an anti-imperialist and anti-militarist at a time when Theodore Roosevelt, after the American victory in the Spanish-American War, was leading the United States into the distant shores of colonialism in Asia. James summed up his belief in the book that national service for the good of the nation could be a substitute for war. That is Carter's concept in calling for a radical restructing of American society.