He used to be known as a dashing monarch, bold and a bit of a playboy - "the James Dean of Arab feudalism." Now King Hussein of Jordan is a somber statesman. So it is notable that he has suddenly abandoned a role of studied quiet in favor of a loud call for a summit meeting of Arab leaders.

I talked with the king about summit possibilities during an interview in his palace. It was our third encounter in the past four months, and I was struck again by the physical marks of change.

Hussein's face is deeply lined now. His hair is graying and his tone somewhat weary. He is growing a beard - "like my grandfather," he said.

I observed that the call for a summit seemed a departure from a period of doing nothing - especially about the peace negotiations between Egypt and Israel. Hussein said he had been active all along in trying to promote cohension among the Arab states. But he conceded that President Sadat's visit to Jerusalem "caught us all completely by surprise . . . We were momentarily paralyzed."

What broke the paralysis was Israel's invasion of southern Lebanon last month. In the past, the king recalled, Israeli attacks had always provoked some kind of military response. He mentioned 1948, 1956 and 1967 as examples.

This time there have been no reactions. But there was "pain and disquiet" among the Arab masses. Those bitter feelings of frustration constitued a mortal danger. They threatened the "wreck of the Arab nation." To avert that he wanted the Arab leaders to get together and develop policies of harmony and cooperation. "We do not want to be the last of the Arabs," he said.

I asked if a summit meeting would not imply an acknowledgement by Egyptian President Sadat that his initiative had failed. "I have always said," the king remarked, "that the Sadat initiative had to have one of two results." One was success, which would mean Israeli withdrawal from occupied territory, self-determination for the Palestinians, and peace. If that occurred, "we would all rejoice."

But, he went on, "we have not had success." On the contrary, he noted that U.N. Resolution 242, providing for withdrawal from occupied lands, was now questioned by the Israelis. he said there was no more prospect of a Geneva conference. He said that after the Lebanon incursion he did not even know "what map of their country is in the minds of the Israeli leaders."

I asked whether he was saying, in effect, that since the Sadat initiative things had moved toward saying, all right, we tried and failed. Let us look at ourselves, and build our strength, so that in time Israel will assume its true proportions, and we can try again. Let us make ourselves strong so the Israelis will know they cannot threaten us."

I expressed doubt it would be possible to convene a summit, especially given the differences between Egypt and Syria. Hussein admitted the difficulty. But he claimed he had encouraging signs from all countries, including Saudi Arabia. "There is a chance," he said, "that Syria will come in."

But an Arab summit looks to me to be way, way in the future. I see no sign that Sadat is ready to give up his peace initiative. Nor that Syria is ready to abandon the so-called refusal front.

My guess is that King Hussein has called for the summit as a kind of defensive maneuver. It puts him in good position to resist any pressure that he join Sadat in talking with the Israelis. it also puts him in good position to open dealings with the refusal front without having to denounce Sadat. It is notable that the Jordanian prime minister had just returned from a visit to President Qaddafi of Libya, a leading figure in the refusal front, with an apparent promise of financial aid to Jordan.

But Hussein's stance involves more than self-protection by a canny man in the middle. He is not merely trying to minimize the damage he will suffer in times bound to be difficult. He is announcing his own judgement - the judgement of a shrewd, experienced, Moderate and pro-Western Arab leader - that Sadat's effort to fly solo has no future.