Hours before taking in an exhibition baseball game in Havana between a Cuban team and the Tampa Bay Rays on Tuesday, President Obama hit a home run of his own with a soaring address to the Cuban people.

“I have come to bury the last remnant of the Cold War in the Americas,” the president declared in an address that hit all the right notes. “A policy of isolation designed for the Cold War made little sense in the 21st century.”

His speech contained the clearest rationale the president has yet offered for his new policy. And he brought it home by reciting a civic credo that holds special meaning for Cubans who have been denied liberty for more than half a century.

“I believe citizens should be free to speak their mind without fear — to organize, and to criticize their government, and to protest peacefully, and that the rule of law should not include arbitrary detentions of people who exercise those rights. I believe that every person should have the freedom to practice their faith peacefully and publicly. And, yes, I believe voters should be able to choose their governments in free and democratic elections.”

These are words that the Cuban people needed to hear. It must have induced heartburn in Raúl Castro, sitting only a few feet away, to hear an American president standing on a privileged stage in Havana declare that “human rights are universal” and that democracy is the way to solve the problems of society.

Those words would be deemed seditious if said aloud by the average Cuban. Some of those political prisoners that Cuba doesn’t have — if one were to believe its president — were locked up for saying much the same.

The assault on the dissidents known as the Ladies in White on Sunday was a stark reminder that the old order still prevails. Castro and his aging hierarchy still call the shots, and they’re prepared to maintain their grip on power by whatever means necessary.

No American policy in half a century has managed to change the authoritarian nature of the Cuban regime, nor is Mr. Obama’s diplomatic initiative likely to have an overnight impact. But it has already changed the discourse between Cuba and the United States.

The core of Mr. Obama’s message was that if Cubans control their destiny, their future can be better than their past. Change comes slowly in Cuba and — as the Ladies in White can attest — painfully. But it begins by believing in the possibility and the dispelling the Castros’ myth that the United States is the enemy of the Cuban people.

Part of that change would involve bringing Cubans and Cuban Americans together in a common effort to improve the place both call home. “In the United States, we have a clear monument to what the Cuban people can build: It’s called Miami,” said Mr. Obama.

His visit was designed to end a half-century of mutual antagonism. The new policy, as we said when it was announced in 2014, remains a gamble. It didn’t work when Mr. Obama tried to reset relations with Islam by declaring friendship with a speech in Cairo in his first term.

But it can be different in Cuba because even a half-century of estrangement has not wiped out the ties of commerce, joint history and common interest that date back well over a century.

Cuba and the United States have been a presence in each other’s history since long before Fidel Castro burst onto the scene, and they will be again.

— The Miami Herald,

March 22