Out of the blood and smoke in Miami there emerges the outline of a historic distinction. It is the distinction between blacks and immigrants, in this case Cuban immigrants. The distinction lies at the heart of this country's racial tragedy.

America, to wave after wave after wave of immigrants, presented itself as a land of opportunity. The Germans, the Irish, the Jews, the Poles and the Italians all came from countries that weren't. By immensely hard work at the most thankless tasks, the first and second generations entered into the dynamic of Amican life. By the third generation they had established themselves as communities able to take care of their own people economically and, if necessary, by political action.

The Cubans of Miami are the latest case in point. Most of those who fled from Castro in 1959 and the early '60s came from middle-class backgrounds. They threw themselves into trade, construction and the professions. They built business, renovated neighborhoods and started schools. They made Spanish a second language in the Miami area, and began to attract commerce and vacationers from all over the Caribbean and South and Central America.

Now, only 20 years later, the Cubans are a force -- maybe the force -- in southern Florida. They are very big in banking, real estate and politics. They showed their muscle when a new batch of refugees began pouring out of Cuba only a few weeks ago. The Cuban-Americans sent boats to ferry their friends and relatives and established medical and legal services to see them through immigration. For a few weeks anyway, their pressure caused the president to suspend the law of the land in an "open arms" welcome to the fleeing Cubans.

A few blacks have also lived the immigrant experience. Those who made it North from the South before the Civil War and recent arrivals from the Carribeans have had the chance to succeed by hard work in tough jobs. Many of them have done exceedingly well.

But the overwhelming majority of blacks never had the immigrant opportunity.

They came to this country as slaves in the 17th and 18th and early 19th centuries. In bondage, everything worked against initiative and the development of community power. Now most blacks are 10th-generation Americans. They have the low economic status of immigrants. But Except in rare cases, the compressed energy that typically drove the first two generations of immigrants has been long since spent.

Instead of forcing their way through the private sector, accordingly, blacks have had to look for improvement to the conscience of the community -- the white power structure or the state. Emancipation is one case in point. The success of the civil rights movement in the 1960s is another. But public conscience waxes and wanes, and in unhappy times the black community tends to become both dependent and discouraged.

The depths of the despair and dependence came home to me on a visit to Miami 10 days ago. Among others, I talked to the local head of the Urban League, T. Willard Fair. Fair denied that Cuban immigration was inimical to black interests. On the contrary, he said, the Cubans improved the local economy and made more jobs available for blacks.

He said that he personally had tried to do something for the Haitian refugees streaming into south Florida. But other blacks, when told that the Haitians were being treated more severely than the Cubans, responded with a shrug. "Their attitude," Fair said, "was, 'So what else is new?'"

Relations with the white community, Fair said, were far less influenced by Cubans and Haitians then by two cases symbolic of the local attitude toward blacks. There was the dismissal of Johnny Jones, the black superintendent of schools of Dade County, after his conviction on charges of using public funds to equip a vacation home. Then there was the McDuffie case, involving four Miami policemen charged with beating a black to death.

As it happened, the four police officers were acquitted last Saturday. Many whites in Miami were, as one of them told me in a telephone interview, "astounded by the verdict." The black community exploded, and there followed the riots and burning and looting of last weekend.

The lesson of all this goes well beyond Miami. It is that all Americans live in the midst of a historic tragedy. The black community has been denied the chance given to everybody else. There is a debt to be paid, and if conscience flags, and spirits grow mean, then in city after city there will be explosions.