Warsaw — The next two days may be even more crucial for Poland's future than the bitter week in December 1981 that brought martial law.
There is a chance that street demonstrations and clashes with police could lead to the bloodshed forecast by the government.
Or, there may be a turning point of the kind the Roman Catholic primate and bishops appealed for in a pastoral letter read in all churches Sunday.
It was an anguished call to government and people alike to show restraint and cooperate in ''easing tension through talks not coercion and violence.''
And a reminder that, ''martial law interrupted dialogue but did not rule it out.''
Gen. Wojciech Jaruzelski also appealed to Poles in a Sunday speech at Poznan to make Tuesday, Aug. 31, ''a day of peace,'' that would ''not be stained by excesses and irresponsible demonstrations.''
If, in fact, the second anniversary of the banned trade union, Solidarity, passes Tuesday without serious conflict, it could provide an opportunity - possibly the last - for the government to reach some kind of accord with this tired and despairing society.
The substantial easing, if not yet full removal, of martial law has become urgent not only for Poles but paradoxically in East-West relations as well.
The West saw a step forward here in the July releases of hundreds of internees and the reduction of many civil restrictions under emergency law.
The Reagan administration, however, said it was not enough.
But since then, the Western alliance itself has been riven by Mr. Reagan's attempt to pressure the Western European allies into backing his pipeline sanctions against the Soviet Union and their refusal to bow to that pressure.
The controversy is seen as threatening the stability of the Western alliance much as the crisis in Poland and Western efforts to influence it came to be seen by the Russians as ''interference'' and posing a dangerous threat to the cohesion of the Warsaw Pact and, therefore, their own security.
An impasse seems to have been reached - with this country at its center - in which an easing of tension in Poland could help reduce the conflict in both Eastern and Western alliances.
Publicly, the Poles still reject any idea of appearing to yield to outside (Western) pressures. But they frankly admit they have a special interest in the relief of present international tensions and are not unaware of what they can do to help.
An immediate step was spelled out by Archbishop Jozef Glemp, to the great religious concourse at Czestochowa Aug. 26.
''Free Walesa,'' the primate said simply. ''Let him express his viewpoint as a free man. Allow the union (Solidarity, though he did not mention it by name), only gradually at the start, to resume its activity.''
Significantly, the specific mention of Solidarity's exiled leader aroused applause that held up the primate's speech for a full two minutes.
Freedom of speech for Walesa and a genuine start to dialogue - not just media discussion - about the future unions, have become the key test of good faith between General Jaruzelski's pledge to continue the 1980 reforms and a still skeptical Polish nation.
Can that skepticism be diminished by the way in which the media - excepting only the Roman Catholic but pro-government daily, Slowo Powszechny - ''censored '' the primate's direct allusion to Walesa and boiled his words down to a plea for general amnesty?
Not long ago, the government seemed still to be counting on the public at large, with time, ''forgetting'' both Solidarity and its leader. It now appears the process has worked the other way.
Most ordinary Poles and a majority of the workers - except the most militant workers - say they are tired of standup confrontations with the authorities. But the idea of independent trade unions has not been surrendered, and Walesa - the man who more than anyone brought them into being - is more than ever their symbol of hope.
Vice-Premier Mieczyslaw Rakowski has just been quoted by a West German magazine as allowing for a conceivable Walesa role in new unions. It was the first time since martial law such a suggestion has been made. (The statement was not reported here).
In the meantime, Walesa still is kept in the total isolation of a forest lodge in sparsely populated southeast Poland. The authorities are still dallying over an understanding with the Roman Catholic Church to move him to more tolerable surroundings nearer his home.
An end to martial law and, therefore, a review of Solidarity's future could both be brought nearer, a senior party official told the Monitor privately, if this week's anniversary days pass without major upset.
That could be implicit in the government's tremendous advance deterrent campaign, first to refute the underground's professed ''peaceful'' intentions in any demonstrations, but, above all, to impress the nation at large that it has all the means - and the resolve to use them - to meet any challenge on the streets.
In his Poznan speech Aug. 29, General Jaruzelski mixed a tough ''no leniency'' warning to the regime's opponents with a new affirmation that ''there is no way back'' from the reforms mapped at last summer's party congress. The aim of terminating martial law ''by the end of the year remains in force,'' he said.
So far, response to the underground's call has been confined to five of the 49 Voivodship capitals. It appears well short of what its initiators hoped for.
Thus the steady escalation of official warnings might also reflect growing government confidence that it had control of the situation but kept up the pressure to the very end to be doubly sure.
It remains to be seen what effect these official warnings or the moderating appeals from the Church will have had. The latter's influence has often seemed less authoritative than in the late Cardinal Wyszynski's day.
Since then popular disappointment and despair, as the bishops said, has grown under what almost all the people still see as a lack of positive reform under martial law .
''The trouble is,'' a young intellectual still committed to Solidarity told the Monitor, ''martial law has moderated neither the hardliners in the party who still think their day will come, nor the extremists in and around the union who really have nothing to lose and can do any stupid thing.''
In a new, major confrontation, the odds are bound to be heavily on the government's side.
For its part, however, Solidarity could lose its opportunity to reappear - barred from politics but meaningfully independent as a union - to build further on the tangible social gains still existing from the original agreements.
Many knew at the time that the economy could not afford the financial benefits conceded by the government then. And it does not appear possible without social peace in Poland. The first move is still up to the government.