HOW RARE that so many fields of human endeavor could lose an enthusiast and pace-setter at once, as happened Monday when John Hay (Jock) Whitney died at the age of 77. For some of us in newspapering, of course, it was the loss not only of a friend, colleague and connoisseur of fine journalism, but also of a close business partner, since he was chairman of the International Herald Tribune, published jointly by Whitney Communications, The Washington Post Co. and The New York Times Co. But consider the many other interests that made him so remarkable:

Mr. Whitney was, in no particular order but never halfway, an investor, sportsman, war hero, philanthropist, play and film producer, diplomat, active promoter of racial harmony, art collector, political fund-raiser, expert on thoroughbred horses and, in the 1930s, internationally ranked polo player.

One thing he definitely was not--though his birth and station made it eminently possible--was a snob; he refused to have his name listed in the "Social Register," calling the publication a "travesty of democracy" with "absurd notions of who is and who isn't socially acceptable." The John Hay Whitney Foundation, main vehicle for his philanthropies, concentrated on providing countless scholarships and other opportunities to citizens "of exceptional promise who, because of arbitrary barriers such as race, cultural background or region of residence, have not had the fullest opportunity to develop their abilities."

As ambassador to Great Britain from 1956 to 1961, Mr. Whitney was instrumental in restoring good relations between the United States and Britain after the strains of the British-French-Israeli invasion of Egypt following the nationalization of the Suez Canal. During this time, he also began investing in The New York Herald Tribune, a widely admired newspaper that, in spite of millions of dollars invested and the gathering of a top-flight newsroom staff, was to merge and then die, a victim not of deteriorating content, but of the complex New York City market in which it competed.

The Herald Tribune name, in the mast of the famous Paris affiliate--now the International Herald Tribune--has lived on, as have other publications in which Mr. Whitney at one time or another invested through Whitney Communications; today, through a susidiary, this corporation has inter- ests in 29 newspapers in Maryland, Delaware and Florida.

Thoughtful, unselfish, vigorous in his determination to help make life better for all citizens--and somehow finding enjoyment in this vast range of endeavors--Jock Whitney was an exceptional friend.