THE ADVANCE WORD on Mikhail Gorbachev's anniversary speech had been that it would rip the veil off 70 years of Communist deception. Either friends or foes could have spread this word: friends to encourage his boldness, foes to build up false expectations. But in the event, the speech was relatively restrained. Some but not much candor was restored to the official reading of Soviet history, notwithstanding Mr. Gorbachev's pledges to leave ''no blank pages.'' Less was said about Stalin's murders, and with less passion, than Nikita Khrushchev offered 30 years ago. ''Selfish'' conservatives and ''impatient'' liberals were paired as threats to reform. The speech was essentially a rationale for tactical caution.

It seems that Mr. Gorbachev is not in total command in the Kremlin. He acknowledges ''a certain increase'' in resistance, and glasnost provides evidence of it. It is not surprising that ambitious plans for change should occasion argument. Mr. Gorbachev is promoting change on a scale that provokes widespread doubt and opposition in the party apparatus and state bureaucracy. Soviet liberals who embrace him have a voice that can be heard outside Soviet borders, but do not have matching political clout at home. His reach for mass support is hindered by the workers' lack of political habit and by the inability of reform to offer early visible improvement in their daily lives.

Exciting things are going on in Moscow. Sobering as it is, however, it is necessary to keep in mind the framework of the debate. Was Stalin's terror and its sequel, the bureaucratic expansionist state, the inevitable and still inescapable result of the Lenin revolution, in which case Mr. Gorbachev is but a blip on the screen? Or is there in the revolutionary tradition a reformist potential, represented historically by Nikolai Bukharin, whom Stalin murdered in 1938?

Mr. Gorbachev introduced but at once dismissed Bukharin in his address on Monday, as though to authorize discussion -- a step forward -- but not to position himself as an heir to Bukharin or to assume the political burden of becoming his champion. That tells a good deal about the cramped context in which the current reform campaign is unfolding. Certainly it should put a brake on premature Western celebration of Mr. Gorbachev's success.