Another act in the old story unfolds in the Caribbean. The papers are filled with accounts of refugees turning up on alien shores, each telling an emotional tale of suffering, of being forced to eat cats and dogs, of families broken and homes abandoned, of risks and daring. And all in the name of freedom. Cuba Libre, 1980.

"I have a problem with the lack of liberty and the limitations on the young," a Cuban mother tells a New York Times correspondent after arriving in Costa Rica the other day.

As always, these episodes strike familiar chords -- the tragedy of great hopes dashed, the affirmation of the human will to resist oppression. But there's another side to the lastest Cuban saga that, in light of Iran, proves instructive for Americans. We who boast of our own revolutionary heritage have not been very successful in understanding the forces that make up other genuine revolutions. And we have paid for it in such disparate places as Iran and Vietnam. That particularly has been the case with Cuba.

More than 21 years has passed since Fidel Castro came down from the Sierra Maestra Mountains to begin his 600-mile triumphal march to Havana. He was only 31 then, and an almost unanimous Cuban public hailed him as an apostle of a new order of justice.

When he reached his destination and faced the masses for the first time as Cuba's leader, three white doves were released. They flew directly toward him, and one perched on his shoulder as he said:

"There is no longer an enemy."

Even then, the U.S. watched Castro warily. We had stood by the ousted dictator, Fulgencio Batista, till the end. Soon plans to topple Castro through our CIA were under way.

As then-vice president Nixon argued pirvately, Castro was a communist and had to go.

What we failed to understand was that Castro, however much he later came to talk about Marxism, was a Cuban nationalist first and foremost. The revolution he led grew out of appalling domestic conditions; it succeeded despite the overwhelming military power amassed against it by Batista's forces who employed the weapons we supplied them and the tactics we taught their leaders in our academies.

Castro's guerillas certainly were not the Robin Hoods so romanticized by elements of the American press. But they considered themselves Cuban patriots fighting to free their homeland every bit as much as do the exiles today, who yearn and plot to overthrow Castro's regime.

If any doubts about these facts remain, they should be dispelled by the publication shortly of a remarkable document. It's called "Diary of the Cuban Revolution," compiled by Carlos Franqui, one of Castor's closest collaborators. His title is misleading. It's not a diary he put together, although he does include portions of his own and other participants' writings. He offers a melange of documents -- letters, interviews, texts of speeches, communiques, broadcasts, with a thread of not-too-helpful narrative exposition to put the events in chronological perspective.

Here we have the words of Castro and Che Guevara, Carlos Rafael Rodriguez and Celia Sanchez, Abel Santamaria and Frank Pais and other long forgotton who formed the heart of the revolutionary cadre. What shines through them is not their ideology but their innocence. They are romantics. Cuba is their love. The glory in their passions, their heroism, their martyrs, their dreams of restoring liberty to Cuba. They are, as Castro said of himself earlier, "quixotic, romatic, a dreamer."

Together they repeat tales of atrocities perpetrated by the government forces. Nothing reported from Iran under the shah eclipses their accounts of barbarisms in Batista's Cuba. At one point they record the methods of torture:

"They insert sharp, pointed objects with electrical current into the male organs or the anus. They drive nails into the body. They hammer sharp, pointed objects into the head. They burn the eyes with electric blowtorches. They tear out the nose of other appendages with pliers . . . ."

On and on, worse and worse. The point is not which regime becomes the more barbarous, but how such actions from the incendiary material of the next revolution.

In his celebration of the Cuban revolution, Carlos Franqui unwittingly helps to explain why events there today seem almost ordained.

He writes of a world without norms in which all myths are real, and goes on to praise his homeland in these words:

"Cuba is an island of immigrants and emigres. In constant movement and danger. Coveted by the great powers. Invaded by buccaneers and pirates. Occupied by Spaniards, Britons, North Americans. An island of sugar and tobacco, of misery and slavery: rebellion itself."

Now we have new evidence of another revolution betrayed, and of people wanting to turn on -- or flee from -- the erswhile liberator.