Sometimes a rare relationship occurs between student and professor. It's usually born on intellectual grounds, but ends up taking root on emotional turf.

Last night's reception at the Cosmos Club was more a meeting of the minds than it was a typical Washington cocktail party. It was given by the former student, Michael R. Beschloss, for the professor, James MacGregor Burns, both of Williams College in Williamstown, Mass. The guest list was made up mostly of students and colleagues.

"If you have to pull out themes about this party, it'd be (A) Williams and (B) writing," said Beschloss, 27, who is now working on a book about the relationship between the presidency and State Department since 1961.

The occasion was the publication of Burns' newest book, "The Vineyard of Liberty," the first of three volumes in a 10-year project about the history of America. Said Burns of the evening, "The best teacher tries to help develop qualities in a student so that the student becomes the teacher's teacher."

But most of the talk, which took place somewhere near the bar or the pate', was about Burns himself.

"Lively, lively, lively . . . " was how Henry Catto, Pentagon press spokesman, described his old teacher, " . . . and tolerant."

"Tolerant of you?"

"Tolerant even of Republicans like me," answered Catto.

Another former student and also a former aide to Walter Mondale, Richard Moe, remembered Burns' political endeavors.

Burns, "turned out to be a better historian and writer than candidate for office," Moe said about the time Burns ran for a district seat in Massachusetts in 1958. "He made you look at government as a public service and that it could do things."