WHAT DO you suppose Gov. Bradford and the Pilgrims of the first Thanksgiving would make of contemporary America? They would certainly disapprove. They would observe that, at great risk, they fled the corruption and arrogance of 17th-century London and Amsterdam only to see that their heirs and successors had built far larger and more splendid cities. The Pilgrims of 1621 would see that, over the years, the turkey supply situation has been satisfactorily resolved. But they would also learn that, thanks to the efficiency of the frozen food industry, the whole idea of the harvest has grown remote and vague in American minds -- less of an annual event in most lives than, say, the opening of the new television season.

Gov. Bradford would be stunned by the wealth visible around him, and he would perceive that money was the least of it. He would see that life spans now average twice the Pilgrims', and infant mortality rates are perhaps one-fifteenth theirs. He would be struck by the easy transportation and the huge houses with their warm rooms. He would note that the only Americans of this generation who chop wood are those who don't care for basketball or jogging.

At that point, the Pilgrims would probably begin asking questions -- the sort that hastened their departure from England. They might ask to what good purposes Americans were using their vast wealth. And they would discover that most people consider themselves to be just getting by.

They would discover that most Americans have fallen into a gloomy state of mind about their prosperity. Most of them think they are getting poorer, or are about to get poorer. The Pilgrims would find that astonishing, amidst such evidence of abundance. Being earnest but tactless people, they might very well point out that great wealth carries with it great power, and therefore great responsibility for the moral welfare of the world. If they asked how that power is currently to be used, they would be told, of course, that Mr. Reagan's transition teams are thinking about that one. But most people feel that American power -- and perhaps American responsibilities with it -- has been shrinking. Gov. Bradford would disagree, and he'd be right.

Thanksgiving is the most deeply American of all the holidays on the calendar. It's not only an occasion for a good dinner -- although a good dinner is truly one of the better things in this world, and there's nothing wrong with a little reflection on the circumstances that bring good dinners to most Americans pretty regularly. But Thanksgiving also recalls the original compact that bound Gov. Bradford's community together in mutual encouragement, inspiration and supoport. The compact has had its good times and its bad times. It has changed a lot over the years, as the governor would be the first to observe. But the compact endures and, along with the dinner, it deserves to be celebrated at Thanksgiving.