The one Western leader who knows both Yuri Andropov and Ronald Reagan - West German Chancellor Helmut Kohl - refuses to join his Western colleagues in worrying about the state of Soviet-American relations.
During a long interview in his office overlooking the Rhine, he explained why.
''For the Soviet Union,'' he said, ''the essential fact is that the Europeans are more united now than they have been in 20 years. . . . History is on our side. . . . I am, in fact, optimistic. The course of events does not favor the Soviet Union.''
Those are extraordinarily strong words, especially for a leader who faces:
1. Demonstrations in the next few weeks that will send hundreds of thousands of his countrymen marching past his office and TV cameras to the center of Bonn.
2. Probable deployment of more Soviet missiles in East Germany in response to the United States Pershing II missiles, whose installation in West Germany begins in December.
3. Possible stalemate of the Geneva arms talks.
But Dr. Kohl remains calm in the face of Germany's so-called ''hot autumn.'' And he counsels calm for other Western leaders.
In this view, barring an unexpected turn of events, the protest rallies will be massive but pass into history. The opposition Social Democrats will vote against the Pershing deployment. But Kohl's conservative coalition will win the parliamentary test vote.
Then, the chancellor argues, the men in the Kremlin will recognize the resolve and probable longevity in office of the Mitterrand-Thatcher-Kohl trio. And Moscow will therefore not halt the Geneva nuclear talks, nor next winter's conventional arms talks in Stockholm. And somewhere along the line he hopes for a Reagan-Andropov summit, despite today's bitter relations.
But he makes this optimistic scenario conditional on two points.
First, he urges unswerving determination to put the big stick - the missiles - in place, unless Moscow agrees to mutual reduction. ''We're going to see this through. In this country, decisions are not made in the street. . . . We're not going to shrink back when faced with force or violence. This is 1983, not 1932'' - a reference to Hitler.
Then he urges speaking softly even while the big stick is used for leverage to push future missile reductions. He repeated several times during the interview his view that Western leaders should remain calm - even friendly - toward the Soviet Union.
Those leaders, he said, must ''remain in the center . . . remain moderate . . . and not run about foaming at the mouth.'' It is important, he added, ''that we continue being friendly . . . and determined - and do not swing the missiles around.''
When Moscow sees that ''the West does not shrink back . . . I'm certain that there will be more negotiations,'' Kohl asserted. But it was apparent that he had more in mind than just the Geneva or Stockholm talks. He spent a major part of our discussion arguing the reasons for a Reagan-Andropov summit.
Where most Kremlinologists take the bitter personal nature of Andropov's recent reply to Reagan's UN-speech offer on missile bargaining as evidence of a period of icy impasse, Chancellor Kohl states confidently: ''One shouldn't overestimate that. How many things have been said about myself . . . .''
At this point he turned from the table around which we sat and pointed toward a painting of one of his Christian Democratic predecessors, Konrad Adenauer.
Kohl said that last year after he became chancellor, Soviet Deputy Prime Minister Leonid Kostandov had paid a visit. Kostandov asked how relations would go between Kohl and the Soviet leaders. Kohl replied that he would ''try to get along'' if each side respected the other's interests. He then pointed to the Adenauer portrait and remarked that Pravda had in the end written that Adenauer was ''a great statesman,'' ignoring all the less complimentary things previously said about him.
Kohl believes deeply that consistent, forthright talk and a conservative policy of Western strength-with-reasonableness will win out with Soviet Politburo leaders. But he is concerned about Kremlin ignorance of the West - particularly of Reagan and the US.
''An important point, which I believe we're taking into account too little in the West,'' he said, is that ''Andropov doesn't know anybody from amongst ourselves. Nobody in the Soviet leadership has been in Western countries. Therefore they don't know the West. The exception is Gromyko. He has a total monopoly . . . He's been foreign minister for 30 years, and he knows everything. He's got a brilliant mind, a brilliant memory.''
But Andropov's dependence on secondhand impressions puts him at a disadvantage, Kohl argues, compared with President Reagan. ''There's a conveyor belt into the White House. Visitors keep flooding in. So the American President within a very short time knows half the world. And then on top of that the President has electoral campaigns to fight and an outgoing personality.''
Soviet leaders, he continued, have few such direct contacts with the outer world. So a summit is needed - not just for completing a well-prepared arms or trade deal, but for personal contact for future relations.
Kohl, whose deep seated self-confidence resembles that of Reagan, believes that the ''chemistry'' of Andropov and Reagan would work in a personal meeting - despite recent strains. ''I do believe that they could come to terms with one another. . . . You can find types of characters that you can tell won't get along - which doesn't have anything to do with politics or the color of your skin or whatever . . . . But I don't believe that such is the case with those two.''
He hastens to add that this does not mean that they would find agreement on issues easy, merely that they could speak candidly and still get on well together.
On his home front, Kohl seems determined to get on well with most of the opponents who will march past his chancellery later this month - even while disagreeing with their strategic logic.
''There are real pacifists among them - religious pacifists,'' he observes, ''and I respect them a lot. . . . If we went out in the street there (we would find) every second person has lost a close relative . . . either in the First or Second World War.''
But the self-confident Kohl is convinced his way of deterring war is safer in the long run. ''It's going to be difficult,'' he admits, ''but we're going to make it.''