IMPRISONED IN 1973, Reza Baraheni is Iran's most famous political prisoner. As a poet, as the "founder of modern literary criticism in Iran," Baraheni is acclaimed to be the most distinguished voice of opposition to the Shah and the Pahlavi regime. To distinguish between literary excellence and what is politically fashionable has never been on an easy task. And among literary people in this country, Baraheni has come to enjoy a kind of moral authority which is more the result of publicity than his merits as a writer deserve.

The subtitle of Baraheni's book is "Writing on Repression in Iran." But his book is actually a disorganized miscellany that contains articles about Iranian culture and history, autobiographical fragments, prison memoirs and, somewhat gratuitously, a selection of the author's poems.

Baraheni is an Iranian, not a Persian. It is a distinction he is careful to make and one that needs to be explained. Iran has 36 million people, and only half a million are Persians, Aryans. The rest of the country is by no means the docile, uniform mass that official Iran makes it out to be. Iran contains many local groups - Kurds, Baluchis, Armenians, Turcomans - whose loyalties have remained not with the Shah, but with themselves.

In all developing nations, nationalism and patriotism soon find themselves at war. We are customed to think of both things as the same, but they are not. Nationalism is the modernizing passion of the nation that wants to catch up; patriotism is the custodian of a country's past. Baraheni is a Turk from Azerbaijan, a northwest province of Iran that borders the Soviet Union along the Aras River. He is a patriot, not a nationalist.

(What nationalism can mean is seen when, at the burial of his father, Baraheni is forbidden to place a Turkish poem on the gravestone because Persian has been decreed the only official tongue.)

In reading his book, one detects again and again his desire to protect the local, peculiar features of Iran from being eradicated, even if they are unprogressive and backward - because they make Iran the country it is.

What maims the reader's interest in Baraheni is the fact he is an ideologue, a writer whose intense and insular prejudices mar much of what is best in his work. The long essay, "Masculine History," which should have been one of the best things in the book, ends by being one of the most half-baked. Baraheni holds what is called "the materialist theory of history," originated by Saint-Simon and restated by Marx and Engels. Briefly, the theory holds that the morals, art, politics of a period are what they are because of the existing modes of production and means of exchange.

Baraheni adopts this assumption and develops - unconvincingly - the idea that the scarcity of water in Iran resulted in a monopoly system which destroyed the position of women and made way for the oppression of men.

"Masculine History" deals with what could have been interesting subjects - the role of the Shahs in Persian history, or the subjugation of women - but the key to the piece is a virulent hatred of the father; the father in history when he calls himself the Shah, and the father in the home as well. The one expliots the nation, the other the family. Baraheni abominates both.

The piece fails, I think, not only because of what is said, but because of how it is said. Much of what passes for idealistic criticism is simply disguished hatred, and Baraheni is full of hatred. "Masculine history" is confused in its learning, and slipshod in its language, with all the shrillness of a sectarian tract. It has eyes only for crime, and its ideas are expressed with an uncouth barbarity of tone. Baraheni seems to take an unholy pride in discovering that so many men could commit such abominations.

Throughout The Crowned Cannibals, Baraheni displays himself as an intellectual bully. he complains of Western intellectuals like hesse and Gide who went to the East because, according to Baraheni, they suffered from "the typical salvationist attitude of the Bourgeois West," which he says consists of looking for a heaven which does not exist.

Yet Baraheni himself is quite capable of writing escapist, salvational Marxist rant: "The total overthrow of monarchy in its final stage of corruption and decomposition will be only the beginning of a great series of social and political changes which will eventually lead to the rule of the popular masses in their own right."

Yet in his sympathy for Iran's women, he is both brilliant and sound. Baraheni is quick to see them as victims of a genetic, racist view of life, held fast in a world without redress, without hope of change or improvement. Not your talent, but your sex; not your actions, but your ancestry; not what you have learned, but what and where you were born - these are what keep you forever fixed in your place.

Still, as a writer of polemics, I think Baraheni very poor. He is not a craftsman, not a man careful of the meanings of the words he uses, sensitive to the congruity of their sound and their sense.

He succeeds only in the "Prison Memoirs." It is only in these pages that Baraheni's talent and distinction come fully to life - because on senses that the authenticity of the experience forces him into the sincerity which produces good prose. When one reads of what he suffered in prison, one gets a sense of how unimaginable and ineffable genuine horror is. To live such moments is one thing; but then to try to find words for what is wordless, to discover either that people do not listen to you - or that, if they do, they do so for the wrong reasons - must be like suffering a new and especially terrible kind of solitary confinement.

His release from prison is a small masterpiece, the language vivd, clear, not a word wasted. It is here that Baraheni seems most deeply himself and that one gets the sense of a brave man made to suffer - not simply by others but also by himself.