WASHINGTON - One might argue that Calvin Coolidge was not the brightest light in the vice presidency. But he was bright enough not to say anything as vice president or president. "I have never been hurt by what I have not said," is a Coolidge aphorism.Sen. Dan Quayle of Indiana has had plenty to say since the day he was picked.

Item: Quayle told David Broder of The Washington Post that the next Republican administration would have to draw a sharper picture of the stakes in Central America, including the threat of American troops being drawn into battle if the Sandinistas consolidate their control of Nicaragua.

Item: In a speech last week, he fractured his metaphors about "Stars Wars" and left the audience wondering if he knew what he was talking about when he used the plot of Tom Clancy's "Red Storm Rising" as the justification for building a weapon to destroy satellites. Then Quayle mangled a line from Indiana basketball coach Bobby Knight. Comparing the offensive weapons of the Warsaw Pact with NATO's defensive systems, Quayle said, "Bobby Knight told me this: `There is nothing that a good defense cannot beat a better offense.' In other words, a good offense wins." What Knight said, and Quayle meant to say, according to his aides, was that a good defense usually beats a good offense.

Item: On a Georgia trip, he said the State Department had done nothing to increase the farm exports. "From time to time you have to wonder . . . whose side they're on." When asked what country and what crop, he could not come up with an answer.

Item: Quayle says he is from a family of modest means. There is nothing wrong with Quayle's being rich. Most Americans, given the choice, would rather be rich, and being rich has not been a serious problem in modern politics.

But the issue for Quayle is that he is not of moderate means. He is a very rich man and he should say so. He will be a major beneficiary of a chain of newspapers in Indiana and Arizona established by his grandfather; in May, a $1.5 billion offer was made for the chain.

One thing Bush has provided Quayle is a top set of handlers. The principal one is Stuart Spencer, a political fox who has been a guru to Republicans from Nelson Rockefeller to Ronald Reagan and knows every trick in the bag.

They have labeled the questions about Quayle's Vietnam service in the Indiana National Guard as "bashing" by the press, and they have done it so effectively that the press by and large has backed off.

The selection of Quayle by Bush is a major issue in this campaign. It was Bush's first "presidential" decision.

In the last 25 years, two vice presidents, Lyndon Johnson, and Gerald Ford, have succeeded to the presidency, and the attempted assassination of Ronald Reagan made a Bush presidency a possibility.

It makes the choice of a vice president in the modern era as important a consideration as any other. If Quayle is not capable of being president, he should not be vice president. And if Bush is elected and something happens to him, it will be too late then to ask whether Quayle is qualified.