The most interesting of Gorbachev's reforms thus far came last week with the rehabilitation of Nikolai Ivanovich Bukharin, one of the old Bolsheviks who helped engineer the Soviet revolution only to fall prey to Stalin's Great Purge.

Bukharin, who served on the Politburo at the time of Lenin's death, was charged with ''espionage,'' ''counterrevolution'' and ''plotting with foreign powers'' to destroy the Soviet government. He was arrested, isolated, mercilessly interrogated, framed and eventually he ''confessed'' in the great Moscow show trial of 1938.

Like five of the other nine Politburo members at the time of Lenin's death, Bukharin was sentenced to death and entered Soviet history as a traitor to the revolution he had devotedly served all of his adult life. Because Bukharin was brilliant and outstanding within the Politburo, he was made a kind of arch-villain in official Soviet demonology.

Though serious observers never believed Bukharin's manifestly false confession, not even Khrushchev attempted to set the record straight. After Khrushchev's fall, interest in rehabilitating Stalin's victims ended -- until recently, when Mikhail Gorbachev indicated his intention to reopen the question of Bukharin's guilt.

Now, 50 years after Bukharin was executed, a commission of the Communist Party of the Soviet Union has overturned the verdict of treason against him. The commission's decision was published a week ago on the front pages of Pravda and Izvestia without comment. But no one who is interested in the evolution of the Soviet government under Gorbachev can let this event pass without further attention.

Beginning with Stalin, Soviet leaders have made the writing and rewriting of history one of their spoils of victory. They incorporate history into politics and rewrite as they go, granting and withdrawing honor, dropping some leaders down the Orwellian ''memory hole,'' reinterpreting the past to make it serve current policies.

To understand why Nikolai Bukharin has been rehabilitated, we must understand what he stood for in Soviet politics and how that relates to the current rulers of the Kremlin.

Bukharin was one of the Politburo members who, during the crucial period after Lenin's death, favored the continuation of the New Economic Policy (NEP) in agriculture and industry. Like Lenin, Bukharin and his allies sought to win the peasants' cooperation by concessions to individual farmers and by utilization of free-market devices. They opposed forced collectivization and forced industrialization and reliance on terror as a principal instrument of social control. These eminently sensible views that had guided the NEP were rejected by Stalin as ''right deviationism.''

The reader may already have noticed that these views bear a striking resemblance to Mikhail Gorbachev's ''perestroika,'' or ''restructuring.'' By rehabilitating Bukharin and his fellow ''right deviationists,'' Gorbachev has given his ideas a pedigree and has reinforced his link to Lenin.

Meanwhile, he has moved to delegitimize the policies of his immediate predecessor, Leonid Brezhnev, a man who clearly ruled in the Stalinist tradition. Brezhnev's statue has disappeared from a Moscow square in which it stood, and his name has disappeared from the square itself.

All this has happened during the same period that Gorbachev's associates have been reexamining and publicizing a major Brezhnev legacy -- the war in Afghanistan. Doubtless the attack on Brezhnev makes it easier to reject his judgment that the control of Afghanistan is vitally necessary to the Soviet Union.

It is all very interesting. Lenin used force when he deemed it desirable, but never relied on terror as a major instrument of domestic or foreign policy. All this revisionism in Lenin's name may presage a broad evolution toward less reliance on force in internal and external affairs -- if Gorbachev lasts.

And he just may. As George Orwell wrote in ''1984'' of just such a totalitarian society, ''To control the present is to control the past. To control the past is to control the future.''