AT 5:30 A.M. daily, when the Rose Garden and South Lawn are in darkness and most of Washington is still asleep, Jimmy Carter sits down to a small, hinged table before a crackling fire in the Oval Office and makes decisions. For two hours before his day officially begins, he attacks stacks of papers, some stamped with the government's highest secrecy classifications. With a felt-tipped or ballpoint pen and a clear, bold hand he checks the option boxes on the decision papers, writes memos to senior aides and adds to official reports his marginal notations and instructions: "be tough," "I agree," "let's move" and, occasionally, "nuts."

Carter is a clean-desk man whose personal rule is to act on all business reaching his desk within a day of its receipt. He is activist in his methods, ambitious in his goals, wide-ranging in his interests, restless in his tendency for comment or command regarding matters great and small. He is a man forever in motion, rarely at rest.

To take the measure of the 39th president as foreign policy manager at the midpoint of his term of office, one must entertain two competing paradoxes at once. The first is that this president is extraordinarily close to the fine print of American foreign policy -- yet his direction often translates as vague, indecisive, unpredictable. The second is that Carter has kept the nation out of war, avoided the flash-point international confrontations which marked the terms of his predecessors -- yet his leadership is derided as weak and spiritless, lacking a sure sense of American purpose in the world.

By this point in their presidencies, Dwight Eisenhower had approved CIA-backed coups in Iran and Guatemala, John Kennedy had launched a bungled invasion of Cuba and withstood the Berlin and Cuban missile crises, Lyndon Johnson had sipatched combat troops to South Vietnam, begun bombing North Vietnam and sent marines to the Dominican Republic, Richard Nixon had widened the Vietnam war to Cambodia and Laos, and Gerald Ford had attacked Cambodia to rescue the crew of the Mayaguez.

Carter, on the other hand, has not had to weather a foreign crisis, in the sense of a physical confrontation with another power. He has not dispatched American combat troops to any trouble spot on the globe, nor has he ordered U.S. covert action operations against any foreign government.

The failure for which he has been constantly attacked is his ineffective stand, with his administration openly divided and his own position in doubt, as events in the Persian Gulf and Africa reverberated throughout the world. He was powerless as Iran exploded from within, smashing the foundations of that strategic country's long-standing U.S. connection. Earlier, he was forced to look on helplessly as Soviet equipment and advisers and Cuban troops poured into Ethiopia by invitation of a radical government to turn back an invasion from Somalia.

Carter's fundamental response to those who believe he should engage American power in such places is that "we can't decide what kind of government Ethiopia shall have or what kind of government South Yemen [now a Soviet staging area on the Arabian peninsula] shall have, or what kind of government Iran shall have." In an interview about his first two years, he noted that when changes of leadership or political system take place abroad, it is often said that the United States has lost ground and should have prevented them. Despite this persistent criticism, the American and international public must understand that "we don't have the ability to intrude ourselves into the internal political structure of any nation on earth and control the political processes there, unless we want to get another Vietnam going."

Given Carter's views, and the political constraints on the uses of American power which he reflects, he may be the nation's first truly post-Vietnam president.

The attacks and criticisms do not seem to daunt him, though some of his closest co-workers wish he would answer back. His wife, Rosalynn, who reads his thoughts better than anyone else, said, "He doesn't worry about things. I'm sure he will admit that he has made some mistakes, but if they're made, they're made, and you go on from there...There's so many criticisms that no matter what decision you make, you're going to be hearing it from all sides. Pretty soon the criticisms lose a lot of meaning." Adjusting to Realities

HIS ACUTE SENSE of the limitations of physical power is in contrast with the breathtaking array of political goals which he brought with him to office: deep reductions in the nuclear arsenals of the United States and the Soviet Union as a step toward complete elimination of nuclear weapons; a comprehensive settlement between Israel and all its Arab neighbors; normalization of relations with China with tight assurances for Taiwan; improved alliances with Western Europe and Japan; a peaceful settlement of racial strife in Southern Africa; reduction of worldwide arms sales; a halt to the spread of atomic weapons; enhancement of human rights; withdrawal of U.S. ground troops from South Korea, and more.

As his aims and ideas collided with realities of the world outside, Carter has muted his language, accepted partial steps instead of sweeping changes, amended his decision-making style and tightened the small circle of foreign policy advisers to whom he reveals himself in deliberation.

In his first year he completed new Panama Canal treaties. In his second year he recognized China and broke formal ties to Taiwan. Early in his third year he is likely to sign a new strategic arms limitation treaty which falls short of his hopes but continues the U.S.-Soviet effort to restrain the growth of their devastating weaponry.

The closest he has come to a diplomatic triumph, the Camp David summit which rescued his flagging standing in public opinion and may have saved his presidency, is yet to be crowned with the projected Egyptian-Israeli peace treaty. Another summit meeting aimed at completing the deal is in the works.

He is at once the most public and the least visible of policymarkers. Carter employs public declaration as a means of creating policy, in deliberate contrast to Henry A. Kissinger's use of secrecy to bypass bureaucratic resistance, and he announces his positions and reactions in frequent press conferences, interviews and speeches.

On the other hand, he works closely on foreign policy with only a handful of highly protective people -- fewer than Kennedy or Johnson, according to experienced hands -- and he has little direct exposure to the working level. It is often difficult for those below or outside to understand what he is doing or thinking, or why. Carter concedes that "there hasn't been an adequate communication" of his ideas to subordinates, and he vows to correct it.

He brought to the presidency moralistic views about what is "right" but little sophistication about the workings of either the international system or the U.S. government. He plunged into study of the whole world, case by case, "like an engineering student thinking that you cram for the exam and get an A," as one official described the effort.

Every problem fascinates him, from Brezhnev's jaw to the Belize channel, and the techniques of learning, deciding and communicating on paper enable him to make his mark in many fields at once. The paper process shields him from the eye and argumentation of others, except for the most trusted aides at the top. One official tells the story of a rare Carter appearance at a meeting of the Special Coordination Committee of the National Security Council, where officials were battling tooth and nail about the direction and consequences of a policy decision.As Carter unexpectedly walked in, voices and positions modulated to a gentlemanly, almost academic exchange. Carter did not hear the arguments in their full intensity, and later made his decision based on a brief and bloodless memorandum, with option boxes placed beside summarized points of view.

Carter is inclined to address each foreign policy problem separately, and he has seemed truly surprised when decisions in one area produced problems in another. Several officials said he lacks an overall strategic sense and a feel for political relationships. "This reflects his lack of a historical memory, or what a lawyer would call a body of precedent," said one official who sees the decisions which flow from the Oval Office. Carter seems to sense his need, and said that he has read more history since becoming president than in all the rest of his life.

The main coordinating mechanism for the Carter administration is his breakfast in the Cabinet Room each Friday with Vice President Walter Mondale, Secretary of State Cyrus Vance, Secretary of Defense Harold Brown and presidential assistants Zbigniew Brzezinski and Hamilton Jordan. Carter values their opinions, and told me he encourages their presentation "in an unrestrained way, without concern for the differences that might arise between them." Another participant described the sessions as the site for frequent debate and even "personal clashes." The frugal president charges his aides $1.75 per week for the breakfast consumed while great decisions are being made. The Personal Role

IN MANY RESPECTS, the most essential fact about Carter's policies is also the most obvious: They are his policies and they reflect his qualities and inclinations, from the ambitious aims to the wobbly implementation. "He makes the big decisions himself," said an official who takes part in the inner meetings. Vance, who traveled 315,000 miles to 33 countries in two years on diplomatic missions -- the equivalent of 13 times around the earth at the equator -- is "the guy in the trenches, running negotiations and the State Department." Brzezinski, who stays at Carter's side, "can sit back and advise the president."

Carter's unflagging personal commitment to the control of nuclear weapons has pushed SALT II toward completion, despite a disastrous start with the Russians and many hurdles and setbacks along the way. From his initial SALT meeting two weeks after Inauguration Day, Carter was involved in deep detail of the U.S. negotiating position. To take an arcane example, he personally considered and decided at least four times to sustain the Defense Department view that airlaunched cruise missiles which are not carried in heavy bombers nor armed with nuclear warheads should not be limited to 600 kilometers in range. Later he decided to give way on this point in a bargain for concessions from the Soviets.

Last spring's neutron bomb controversy, interpreted by many as another sign of his aversion to atomic weapons, was a particularly interesting and still mysterious case of personal decision-making. In this situation, Carter the policy maker may have owed much to Carter the former naval officer, who learned at radiation safety school the cataclysmic effects of atomic weapons and never has forgotten them.

Relaxing at St. Simons Island, Ga., in mid-March last year, the president was presented with a memorandum, approved by Vance and Brown, recommending that the United States inform NATO allies of a decision to begin production of the "enhanced radiation" weapons. A deployment decision was to be delayed, ostensibly to give time for negotiations with the Russians but also because the West German government was not ready to endorse placement of the weapon on its soil.

Eight months of negotiations with the Europeans, with Carter's knowledge, lay behind the State-Defense recommendation, but he had not fully focused on the question. When presented with the final decision paper, he unaccountably refused to sign. Consternation spread rapidly through the bureaucracy. The issue erupted politically after the leak to The New York Times of what is now described as a "contingency cable," never approved, telling a U.S. diplomat to inform the British and Germans that Carter had flatly turned down production of the weapon (rather than "deferring" it.)

Some of the president's closest aides have expressed the belief that he made his decision essentially on international political grounds -- to shield the Germans from a difficult situation and sap the force of Soviet propaganda. Others have said part of his resolve, at least, was that "it went against his grain" to create a new type of atomic weapon. Carter, asked recently which interpretation was correct, answered simply, "Both."

Concerning China, he declared in a small White House meeting on June 30, 1977, that he was determined to move ahead with normalization providing he could obtain assurances on Taiwan because "it is the right thing to do." He said then that "I've never gained anything from procrastination" and decided that Vance would lay out the U.S. requirements for the Chinese on his forthcoming trip to Peking. Carteral weeks later, as U.S. and Panamanian negotiators neared agreement on new Panama Canal treaties, evidently because Peking and Panama at once would have been an indigestible load of controversy for Congress.

Within days of the final Senate vote approving the canal treaties, Carter was ready again to move ahead with Peking by sending Brzezinski to the Chinese capital. Following Brzezinski's May 1978 trip, Carter approved a Vance memo which set mid-December as the most favorable time for normalization. (Vance thought at the time that SALT II would be finished by then.)

The president approved the written instructions for both the Vance and Brezezinski trips line by line, as he has with most high-level negotiations. As the normalization talks developed in the second half of last year, he personally cleared the details of each of the six presentations which Ambassador Leonard Woodcock made to the Chinese Foreign Ministry. Eventually Carter edited the statements to be made by the United States and Chinese sides in announcing the agreement on full diplomatic ties last Dec. 15. 400 Letters

EVEN MORE than his predecessors, Carter is deeply impressed at being in the select circle of heads of state and likes to deal with them personally whenever possible. In two years in the White House he met 43 heads of state at home and visited 29 overseas. He has carried on an extensive correspondence with foreign leaders -- more than 400 substantive letters dispatched from the Oval Office.

Carter's personal involvement reached its high point in the effort to achieve a peace agreement in the Middle East, and particularly in his attention to Egyptian President Anwar Sadat. Carter saw Sadat as crucial from the first, and had two lengthy meetings with him in Washington and a stopover meeting with him in Aswan prior to last September's marathon summit meeting at Camp David.

Carter has written more than 30 letters to Sadat, including a fateful handwritten message, sealed with wax and handed to an Egyptian embassy courier on Oct. 24, 1977. Carter told Sadat that the drive toward a Geneva peace conference was descending into procedural squabbles, and he appealed to the Egyptian leader on the basis of their personal relationship to take strong but unspecified action to rescue the hopes for peace. Two weeks later, after first proposing to Carter an impractical scheme for an Egyptian-Israeli-Syrian-Jordanian-PLA-American-Soviet-chinese-British-French summit meeting in Jerusalem, Sadat announced his stunning plan to take a plea for peace to the Israeli Knesset.

The 13 days of Camp David, Carter's high-stakes gamble undertaken with no assurance of success, stands as the high point of his personal diplomacy. Its ups and downs have been recounted in detail. What is not well known, however, is that basic agreement to an Egyptian-Israeli peace treaty was not among even the objectives as assessed in advance by the White House, and that Carter drafted the core of the bilateral accord in his own hand and at his own initiative midway through the Camp David meetings.

Later, in preparation for the Blair House talks which aimed at completing the treaty, Carter obtained a huge map of the Sinai from the CIA and with the aid of U.S. geographers drew the interim withdrawal lines and final military zones for submission to the Egyptian and Israeli negotiators. He also worked on the details of the proposed 10-article treaty which the U.S. presented to the two sides at the outset of the Blair House negotiations.

All this, in the absence of commensurate progress toward agreement on the West Bank and the Palestinian question, represented a major turn toward a bilateral Egyptian-Israeli accord rather than the comprehensive Mideast peace Carter had steadfastly promoted before. As in his watering down of SALT II objectives from deep cuts to marginal reductions in strategic weaponry, Carter took a pragmatic approach under pressure without formally giving up his more ambitious goal. The great question in these areas, as in human rights, nuclear proliferation and other fields where he has had to compromise, is whether and to what extent he will persist in pursuing the long-term objectives. Conflicting Views

"CARTER does good things badly," said an official who has watched with dismay the ragged implementation of positive ideas. A central problem, in this view, is that Carter does not know how to handle internal disagreements among his chief advisers, leaving the bureaucracy, the public and foreign governments confused about U.S. policy.

Carter starts his official day with Brzezinski, who is usually allotted the first half-hour for a national security briefing, and he ends the day with a written personal report of four to five pages from Vance. The tension and interplay between those two men and their personal and institutional viewpoints marked the administration's first two years. Beyond the personalities, Vance and Brzezinski represent fundamentally different views of U.S. policy toward Russia. The question is central to the U.S. stance worldwide, and at the midpoint of the Carter presidency it remains an enigma.

Vance, a former deputy secretary of defense and manager-turned-critic of the Vietnam war, is unimpressed with "Russians are coming" arguments and tends to view conflicts in the world peririphery in local terms where they can be most effectively handled. Brzezinski, described by a fellow White House aide as "the first Pole in 300 years in a position to really stick it to the Russians," tends to see Soviet actions in a global pattern. The implications which flow from these diverse views of Moscow's intentions are large: Vance is inclined to persuasion and negotiation with the Russians, Brzezinski to contention and confrontation.

Carter has delivered four speeches on Soviet policy, the last and most important being the Annapolis address last June 6 which he wrote himself. For all the words, he has never made clear his own basic instincts or essential beliefs and, when asked, tends to speak in both positive and negative generalizations (see box on Page C5).

A close associate said, "Carter wants to get along with the Soviet leadership, but not at any price. He can't be typed. He tends to take a pragmatic view, and wants to look at the options and forward risks in any steps we take." Another senior policymaker described the president as "an anomaly" on Soviet affairs. "He has broad and liberal aspirations which incline him toward peace, arms control and detente. Yet the conservative side of him will not be pushed around and is strongly concerned with security." This official said Carter may have come to office with simplistic views about the Russians and be having a difficult educational process.

Asked if Carter has any gut instincts about the Russians, another of his closest advisers responded: "His visceral feeling is that if he could ever sit down and spend two, three or four days with [Soviet President Leonid] Brezhnev, he could correct many of the difficulties. If he could just get his hands on Brezhnev, he'd feel better." The Soviet and American leaders have in common intense concern about nuclear war and weapons. Their failure to meet in the first two years, because the Russians insisted the two sides have an agreement ready to sign at their summit, may have affected U.S.-Soviet relations in a major way. Time Running Out

AT THE MIDPOINT of his term, Carter seems notably aged by what he has been through, his hair much grayer, his face more lined. Answering foreign policy questions from the same orange wing-backed chair where he sits to do his paperwork every morning, he sat ramrod straight, a reminder of his days as a naval midshipman, and seemed tense. Iran was collapsing, he had for the first time admonished State Department and National Security Council officials to get on the team, and it was Friday afternoon of a difficult week.

The third year of a presidential term is typically a period of hardening lines within the government, the exodus of some officials back to private life and the last chance to accomplish major enterprises before election-year paralysis sets in. Carter and his foreign policy team are aware that time is running out. With the world still erupting and bedrock shifting in nearly every quadrant, Jimmy Carter may find it even harder than before to follow the injunction of his favorite high school teacher, Miss Julia Coleman, quoted in his inaugural address, to "adjust to changing times and still hold to unchanging principles."