''I cannot forecast to you the actions of Russia,'' Winston Churchill told the British people in a radio broadcast in October 1939. ''It is a riddle wrapped in a mystery inside an enigma.''

You can say that once again, in October 1987 -- as Jeane Kirkpatrick just did. The still-unexplained seven-week absence from public view of Mikhail Gorbachev, she wrote, is a reminder ''of how much we do not know and often cannot find out about the great power with which we so often deal on matters of supreme importance.''

We should think about that, Kirkpatrick rightly argues, as we contemplate ''momentous decisions'' on a zero-zero deal for intermediate-range nuclear forces (INF); a follow-up agreement to cut strategic nuclear armaments on both sides by 50 percent; and some sort of compromise on the development of nuclear defense systems. ''The verification of the whereabouts of anything,'' she warned, ''is very difficult in a closed society.''

Quite so. We should be wary of the Soviet Union's sneaky, secretive ways and concerned that, as Kirkpatrick says, Soviet politics ''remains almost wholly hidden from view.'' But if it's agreed that some sort of reasonably safe and sound relationship with the Communist world is worth struggling for, we should also be aware that there is more to the struggle than the hazards and handicaps for our side in having to deal with a ''closed society.''

If we are talking about the United States and the Soviet Union doing business with each other, the question is not which system is ''closed or open,'' but which presents the more difficult riddle for the other to unwrap.

When we find the Soviet society difficult to penetrate, even in the era of Gorbachev's glasnost (which few Americans entirely trust), we should put ourselves in the shoes of the Kremlin's most knowledgeable ''Americanologists.'' Try to imagine their efforts to explain us to their masters -- to measure our motives, guess our intentions, fathom our ''politics.''

What could they be expected to make of the administration's purposes in the Persian Gulf, when the administration itself is pictured in the American media as deeply divided and when its authority to deploy naval forces there in the first place without congressional consent is regularly challenged on Capitol Hill? What sense can they make of a U.S. government in gridlock over aid to the Nicaraguan contras?

Even as the executive branch labors to negotiate the terms of an INF agreement, Congress is trying to legislate the terms. The threat of a refusal to ratify the end result is already in the air. The Soviets have the example of the unratified SALT II treaty as a reminder that the signature of an American head of government is not the last American word.

Gorbachev's mysterious disappearing act and the consequent rumors of illness or power struggles, Kirkpatrick says, ''reminded seasoned Kremlin-watchers'' of similar instances in the past: Lenin's long, unacknowledged illness, the secrecy surrounding Andropov's health, Nikita Khrushchev's sudden fall from grace. Of the latter, she notes that Western experts were as surprised as Khrushchev. Surely if Khrushchev was surprised, Western experts could hardly expect to have the inside story.

Just as surely, it would be better if Soviet society were a lot more open, not just for our convenience but for the sake of the Soviet people. But it is not as if American presidential illnesses had never been concealed, or that (witness the Iran-contra affair, Watergate, Vietnam) the business of the U.S. government is an open book.

The difference is that sooner or later, though not always in a timely fashion, we let it all hang out. This may be even more befuddling to those Kremlin Americanologists.

That's their problem, you may well say, and you are right. The fact that we haven't a clue who will be president a little more than a year from now (and with what foreign policies) may be something for us to celebrate as the American way. As Henry Kissinger put it to a dinner gathering here the other night: ''Many of our problems are caused by qualities that make America such a nice place to live in.''

That's the point. Verification of a whole lot of things can be almost as difficult in its own wonderful way in an open society as in a closed society. But for this we pay a price.