This week opens a new chapter in the foreign policy story of the Reagan administration.
American Secretary of State George Shultz is in Europe on his own for the first time since he took over management of United States foreign policy almost five months ago.
More important than being his first solo in the job is the fact that during the past five months he has become the trusted agent of the President in world affairs and has already recast the mood, tone, and face of the American attitude toward the outside world.
The Europeans who talk with him on this trip are talking to a man who can deliver on anything he may promise to do. He can deliver because he knows his President and will promise only what he knows the President will accept, or what he is sure he can persuade the President to accept.
Also, they will be talking with a man who has already participated in the quiet jettison of those attitudes, postures, and policies that caused the most trouble within the alliance - when US foreign policy was dominated by friction between the White House and Secretary of State Alexander M. Haig.
During that earlier period friends and allies could talk with the American secretary of state, but they could never know whether he represented the President or could deliver on his projects.
A lot has changed since Mr. Shultz came back to Washington June 26 as Reagan's nominee for secretary of state. He held an opening press conference that day saying: ''My name is George Shultz: I'm from California.''
Ever since he has been like that: direct, declaratory, avoiding poses and flamboyant and emotive words. He has not made a threatening headline since taking office. But he has done a lot of listening to others who have played roles in foreign policy before Mr. Shultz came back to Washington.
On the day after he took office he called in Henry Kissinger, who had probably done more than any one other individual to shape the foreign policies that the Reagan administration inherited from its predecessors.
He also called in Zbigniew Brzezinski, the national security chief during the Carter years. He held weekly talk sessions with these two and many others. From such sessions he built up a detailed knowledge of the background of the policies that had existed more or less consistently through the Nixon-Ford-Carter years.
The above helps to explain why under Mr. Shultz there has been a quiet trend in operating policy back toward the pre-Reagan directions. Bristly anti-Soviet rhetoric has been deleted. Pipeline sanctions against the Soviet Union have been lifted. A beginning has been made toward reviving a dialogue with the Soviets.
Relations with mainland China seem to be getting back on track after nearly being derailed over love for Taiwan.
Permissiveness toward Israel has given way to a serious effort to get the Camp David process going again. The White House and State Department are both trying to dissuade Congress from voting an extra half-billion-dollar subsidy to Israel.
And, perhaps as important as the above, is the simple fact that Mr. Shultz is spending 12 days working his way around Western Europe talking to old friends and colleagues about ways of containing trade wars within the Western community.
On the plane to Europe at the start of this trip Mr. Shultz was talking about a desire for ''constructive relations'' between his own country and the Soviet Union. He said the US would welcome any ''substantive moves from the Soviet Union.'' He talked about the possibility of useful ''negotiations'' with the Soviets.
And notice that the changes in tone and emphasis in foreign policy words and deeds have not been accompanied as they were during the Haig days by a background of ''leaked'' criticism from the White House staff.
Not since Mr. Shultz came to Washington has there been the verbal battery fire between the White House and State Department that enlivened the Haig era for journalists but made it difficult for friend and foe alike to know what was really going on in Washington.
There is of course plenty of difference of opinion in the shaping of policy behind the scenes, but it is kept within the family. And there is substantial unity once a policy decision has been reached.
As Mr. Shultz works his way this week from Bonn through Brussels and The Hague to Rome, Paris, and finally to London, those who talk to him will find it worth their while. He knows how to listen. He knows how to promise only what he can deliver. And if he has anything to sell he will know how to present it in reasonable terms.
Of course he will want some things that several allies may find it difficult to grant. One problem will certainly crop up over restraints on trade with the Soviets. And what about lifting sanctions against Poland if martial law is lifted?
Mr. Shultz must argue for keeping sanctions until the Polish government agrees to resume a dialogue with the officially-banned Solidarity. Domestic politics make this mandatory in Washington. The Polish wards of Cleveland, Chicago, and Milwaukee require it - or are deemed to require it.
But if Europeans feel they must resume normal relations with Poland they will find that disagreement with Washington will be easier to manage than in earlier times. Mr. Shultz understands the art of compromise and concession among friends.