The foreign affairs book of the season -- all seasons -- comes in a plain brown wrapper from the House Foreign Affairs Committee. It is by a Library of Congress specialist whose name is not quite a household word, Joseph G. Whelan, and it is an absorbing review of the nitty-gritty of Soviet-American diplomacy over the years. Diplomats, politicians and students of the world should rush down to the committee or to the Government Printing Office for a copy.

Whelan assembles in one handy place a broad range of material from memoirs, histories and some recent interviews bearing on the actual conduct of Soviet-American diplomacy since the Bolshevik Revolution. He offers an analytical gloss of his own, but the meat lies in his focus on the actual negotiating process, the tactics on both sides, the business behind the scenes.

The result is like sitting down for a personal chat, one centered on the juiciest parts of their experience, with a good number of the Americans most experienced and knowledgeable in dealing with the Russians over the years. Even to someone who fancies himself reasonably familiar with the period and the literature, "Soviet Diplomacy and Negotiating Behavior: Emerging New Context for U. S. Diplomacy" is an eye-opening treat.

Its prime value is to remind us of some simple things that presidents in a hurry, diplomats caught up by personal visions and inattentive citizens tend to forget: there are no shortcuts. The Russians are tough customers and can be dealt with seriously only by serious people. The only questions that lie between the Soviet Union and the United States are tough questions. Beware of medicine men.

There is nothing novel or dramatic about this message, but that is precisely the point. Politics in a democracy puts great pressure on policians to promise breakthroughs in Soviet-American relations. From time to time, diplomats emerge who seem to mystify diplomacy, to make of it a special process that, in the hands of a special person, can produce almost magical results.

But a close look at the record, such as Whelan provides, can only demystify diplomacy and restore perspective to the ambitions of politicians. It is, or should be, a humbling exercise.

A second lesson emerges from Whelan's book, and it is that there is something in Soviet-American diplomacy called technique. It would not seem necessary to make the point except that it has often been overlooked. In fact, some ways of dealing with the Russians are better, than other ways. Some diplomats are better than other diplomats. The cards are the cards, but some people win at poker and some lose.

The odd thing is that there is no real secret, and no real disagreement, about what good technique is in negotiating with the Kremlin: set an achievable goal, prepare well, be firm in pursuit, be patient, yield nothing for free, don't count on good will, and so on. Through Whelan's pages march a long line of American diplomatic practioners underlining these time-tested rules: Lend Lease and wartime cooperation negotiator John R. Deane (Whelan's favorite), Averell Harriman, Richard Nixon, and so on. Yet these rules are not uniformly respected, even by people who pride themselves on being professionals. Pressure, disorder, excitement, vanity lead good men astray.

Yet -- and here is the last lesson I would take from Whelan -- the Russians are human, too. A tendency has arisen among Americans to think of the Russians as, in Hal Sonnenfeldt's phrase, "infallible supernegotiators." Their purposefulness, their slyness and secrecy, their very Russian-ness is set against our casualness, openess and American frivolousness.

But the advantage so easily accorded to the Russians is more a measure of our anxiety and misperception than their consistent performance. The record makes plain that Soviet negotiators are capable of poor judgement. It makes plain that over the years Americans have had their share of successes. We are not only obligated but entitled to be of stout heart.

Get Whelan's book. Give it to the college sophomore, the diplomatic negotiator, the restless congressman and the presidential candidate of your choice. Nothing they'll read for a long time will improve American diplomacy more.