Exiled Soviet author Alexander Solzhenitsyn yesterday denounced western society, which he said has taken on a terrible similarity to the state-controlled societies of the communist world in its suffocation of spiritual life.

In a bleak and powerful speech at Harvard University's commencement, Solzhenitsyn said "our spiritual life" has been lost in both the West and the East, and he called for a "spiritual upsurge."

The Nobel Prize laureate came to Harvard from his seclusion in Vermont to deliver his first major speech in three years.

He titled his speech "A World Split Apart," but it could as well have been called "The Decline of the West."

After prefacing his address by saying "Truth seldom is pleasant; it is almost invariably bitter . . . but I want to stress that [my speech] comes not from an adversary, but from a friend," Solzhenitysn launched a long, scathing attack on western society as morally bankrupt.

Though he termed Soviet-style communism "zero and less than zero," he told the audience: "But should someone ask me whether I would indicate the West such as it is today as a model to my country, frankly I would have to answer negatively. No, I could not recommend your society in its present state as an ideal for the transformation of ours."

In an echo of a theme of some of his essays, Solzhenitsyn deplored contemporary man's loss of "the concept of a Supreme Complete Entity which used to restrain our passions and our irresponsibility."

He attacked moral cowardice and the selfishness and complacency he sees in the West.

Materialism, sharp legal maneuvering, a press that invades privacy, "TV stupor" and "intolerable music," all contribute to making the western way of life less and less a model for the world, he said.

"A decline in courage," Solzhenitsyn said, is the most striking feature of what he called "spiritual exhaustion" of the West.

"The forces of evil have begun their decisive offensive, you can feel their pressure, and yet your screens and publications are full of prescribed smiles and raised glasses. What is the joy about?"

"To defend oneself, one must also be ready to die; there is little such readiness in a society raised in the cult of material well-being," Solzhenitsyn said.

He denounced western politicians and diplomats in general for their weakness in dealing with Moscow, but the only person he singled out was former ambassador George Kennan for arguing that moral criteria cannot be applied to politics.

"On the contrary," he declared, "only moral criteria can help the West against communism's well-planned world strategy." Solzhenitsyn spoke a day after President Carter delivered the toughest statement of the Carter adminstration's Soviet policy and told Moscow it must choose between confrontation and cooperation.

After the address, he announced to reporters that the Soviet Union is about to begin the trial of Alexander Ginzburg.

He said Ginzburg, who distributed the funds Solzhenitsyn provided from book royalties to help political dissidents in the Soviet Union, is about to be "swallowed up" by the Gulag Archipelago - Sozhenitsyn's name for the Soviet network of prison camps.

Ginzburg will be tried in the remote city of Kaluga away from any western eyes, Solzhenitsyn said. His announcement about Ginzburg was interrupted when he saw a sign in the crowd saying: "You Can't Fight Stalinism With Fascism."

Angrily pointing a finger at the sign, Solzhenitsyn declared that it is easy for those without experience of Soviet prison camps who live far away from the Soviet Union to call him a Fascist.

The writer, who was sent to the camps during World War II for a private criticism he made of Stalin's conduct of the war, told the sign carriers that he would like them to have first hand experience of the camps.

In a passage the brought some hisses as well as scattered applause during the speech, Solzhenitsyn criticized the U.S. protest movement against the Vietnam war.

Speaking in the heart of a campus which, like many others, was the scene of angry student demonstrations against U.S. involvement in Vietnam, Solzhenitsyn said, "the most cruel mistake [of U.S. policy] occurred with the failure to understand the Vietnam war.

"That's small Vietnam had been a warning and an occasion to mobilize the nation's courage," he said, but the anti-war movement "wound up being involved in the betrayal of Far Eastern nations, in a genocide and in the suffering today imposed on 30 million people there."

Kremlin officials, Solzhenitsyn, said laugh at American "political wizards" for their naivete in world politics.

The bearded author was expelled by Soviet authorities in February 1974 and after a year in Switzerland bought a residence in Cavendish, Vt., where he has lived in almost complete privacy for three years. His wife has said that Solzhenitsyn spends 13 hours writing every day.

Solzhenitsyn attacked the western press for publishing government secrets, making heroes of terrorists and for reflecting more clearly than any other part of society the "hastiness and superficiality" that he called "the psychic disease of the 20th century."

The press, he said, has greater power in the West than legislatures, executive branches or judiciaries. He deplored its "changeless intrusion" into the privacy of well-known people under what he called the false slogan that "everyone is entitled to know everything."

The crowd of close to 20,000 graduates, alumni and friends applauded Solzhenitsyn frequently during his long speech as it was translated into English by Irina Alberti. He was also hissed on a few occasions, mostly from the area where the class of '78 was sitting.

Solzhenitsyn's denunciations of materialist well-being came after several Harvard alumni had received loud applause as they announced record money gifts to Harvard from several of the classes here for reunion festivities.