For some, President Reagan's Middle East peace initiative was the first speech of what one administration official calls "the post-Haig era" of increased presidential visibility in foreign policy.

For others, it was another demonstration of Reagan's sense of political timing, coming just two months before the Nov. 2 congressional elections.

But his closest aides portrayed it as confirmation that Reagan, after 20 months in office, has at last begun to explore the larger purposes and possibilities of his office.

"I think the president's getting more comfortable in the presidency," said Reagan's deputy chief of staff, Michael K. Deaver. "He's more at ease. He understands better how to use the power of the office."

Others less devoted to Reagan might say that the president has devoted his current vacation trip to two of the things he does best: riding horses and making speeches. But it is clear that Reagan now sees himself as less of a johnny-one-note president devoted simply to reducing government growth and standing up to the Soviets.

"The speech the president gave last week was one he wanted to make, and one he feels strongly about," a close adviser said. "He takes seriously the role of peacemaker, and he is convinced that the time is right for the United States to play more than a mediating position in the Middle East."

It was an open secret within the administration in 1981 that the president felt uncomfortable in the realm of foreign policy. His first-year news conferences displayed only a fleeting acquaintance with some of the longstanding U.S. policy precepts.

They also revealed some striking examples of ignorance, such as the occasion on June 16, 1981, when Reagan described the defensive surface-to-air missiles the Syrians had placed in Lebanon as "offensive weapons."

Part of the problem was that Reagan, a two-term governor of California, was familiar with budget issues but had almost no direct experience with foreign affairs. Another part of it was that he concentrated his energies during the first year almost exclusively on his economic program, particularly after the assassination attempt little more than two months into his presidency.

But a larger part of the problem, as portrayed by those around Reagan, was the difficulty of his relationship with Alexander M. Haig Jr., who as secretary of state guarded his prerogatives and battled constantly with Secretary of Defense Caspar W. Weinberger and a White House he apparently felt was undercutting him.

Reagan, unless aroused, tends to withdraw from personal conflict. He values a harmonious working atmosphere highly, and he stepped back from many of the personal controversies within his administration. This had the effect of removing him from policy controversies as well and keeping him relatively unconversant with foreign policy.

The result was that while Reagan was frequently an initiator of economic policy -- going so far as to overrule his advisers when he disagreed with them -- he was so reactive on foreign affairs that serious questions were raised about whether the administration even had a foreign policy.

Deaver said he believes one of the most important developments of the Reagan presidency is the trust that has grown up between the president and his new secretary of state, George P. Shultz, who also has developed a harmonious working relationship with Reagan's valued confidant, national security affairs adviser William P. Clark.

Shultz impressed Reagan with a concise and careful evaluation, presented to the president before Reagan's European trip in June, of the attitudes of European governments. There are those in the White House who believe that the contrast between this presentation and the aggressive advocacy of Haig did much to hasten the change in secretaries of state. Reagan, unless aroused, tends to withdraw from personal conflict. He values a harmonious working atmosphere highly, and he stepped back from many of the personal controversies within his administration. This had the effect of removing him from policy controversies as well and keeping him relatively unconversant with foreign policy.

"Ronald Reagan would never have given the speech he gave the other night if Al Haig had still been secretary of state," one senior official said last week. "Al Haig would have given it -- if it had been given at all."

In part, the official was commenting on what he regarded as Haig's "obsessiveness" about being the sole foreign policy spokesman. But the official's larger point was that Reagan, until recently, would not have felt comfortable in making such a bold speech.

After Clark became national security adviser at the beginning of the year, he initiated a series of long-overdue briefings designed to improve Reagan's grasp of foreign policy. When Shultz became secretary of state he brought in experts on Middle East policy to brief the president extensively and answer his questions. As a result, Reagan has begun to demonstrate a grasp of policy issues on which he previously had deferred to others.

Reagan makes no pretense of being a detail man. He sees his role as that of a chairman of the board, who considers options and makes decisions, then delegates the implementation of those decisions.

His strength as an executive in Sacramento and Washington has been that he makes decisions and hews to a course once the decision is made. His weakness, particularly in foreign affairs, is that he sometimes had lacked the conceptual background and specific information for making a decision.

The Middle East speech was a particularly bold step for Reagan because of his strong feelings toward Israel. The Hollywood film community was ardent in its support of Israel at its birth in 1948. As Reagan changed his politics gradually from Democratic liberal to Republican conservative, he remained unswervingly committed to the support of Israel.

He is today, and, on the helicopter flight from his ranch to a Los Angeles television studio Wednesday night, added to a sentence to his talk. The speech had said, "America's commitment to the security of Israel is ironclad." To this he appended: "And, I might add, so is mine."

Despite this commitment, Reagan has had second thoughts about the even-handedness of U.S. policy in the Mideast since last year, when Israeli Prime Minister Menachem Begin met with him in the Oval Office and then went up to Capitol Hill to lobby against Reagan's decision to send sophisticated airborne warning and control system (AWACS) planes and equipment to Saudi Arabia.

An official said Reagan regarded this action as "arrogant and inappropriate" for a head of state visiting a foreign country. Reagan's skepticism about Begin was deepened this year by the civilian casualties in Lebanon. White House officials confirmed Friday that Reagan did use the word "holocaust" in an angry Aug. 12 phone call to Begin protesting the heavy Israeli shelling of Beirut.

Reagan's growing confidence in foreign affairs is not limited to the Middle East, according to aides.

The president is described as remaining convinced that U.S. sanctions against firms shipping equipment to the Soviets for use on the natural gas pipeline to western Europe ultimately will delay construction. He was not deterred by an internal CIA report contending otherwise or by the sharply worded description of his staunch ally, British Prime Minister Margaret Thatcher, that Reagan's action was "betrayal by a friend."

Those who have talked to Reagan about the subject said he believes that as pipeline construction proceeds there will be growing protest in Europe against Soviet use of "slave labor" to build it.

Overall, the contrast between Reagan on this vacation trip and the Reagan of a year ago is striking. In August, 1981, White House counselor Edwin Meese III did not even bother to awaken the president after U.S. fighters shot down two Libyan jets in a dogfight over the Gulf of Sidra. The event seemed to symbolize the president's withdrawal from his administration into a disengaged presidency run by his advisers.

Reagan is still far from demonstrating the dominant command of foreign policy displayed by his original political idol, Franklin D. Roosevelt, or by such Republican presidents as Dwight D. Eisenhower and Richard M. Nixon.

But as Reagan rode the range this week he was portrayed as no longer content simply to turn over his foreign policy to those who have had more experience in such matters.