America’s big birthday has come at a bad time. On Saturday it will be a divided nation that marks 250 years since 13 North American colonies declared their independence from the Great Britain of George III. Many will be anxious that the republic they established that day is fragile – not least because of the would-be emperor in the White House.

Some will console themselves that hope and angst have always been intertwined in the American story. From the very start, confidence in a bright, exceptional US future was combined with foreboding and doubt. At the close of the 1787 constitutional convention, a woman approached one of the founding fathers, Benjamin Franklin, to ask if the delegates had established a monarchy or a republic. Franklin’s answer: “A republic, if you can keep it.”

Some of that unease was the result, one hopes, of a quiet understanding that the new nation had arrived with a birth defect, in the form of a terrible contradiction. The declaration proclaimed that “all men are created equal”, which excluded women and could not be squared with the fact that this new entity was founded on slavery. That text’s principal author, Thomas Jefferson, was himself a slave owner, and the knowledge of his hypocrisy haunted him. “I tremble for my country when I reflect that God is just: that his justice cannot sleep for ever,” he wrote.

But that fear for the future also owed something to the sheer scale of the founders’ ambition. As Tom Holland, historian of the ancient world, puts it, the US was “founded as a simulacrum of the early Roman republic. And the lesson of Roman history is that at some point, a republic will become an autocracy.” The ink was barely dry on the 4 July declaration, says Holland, when Americans started “dreading the emergence of a Caesar”.

All of which might encourage today’s Americans to be sanguine, reassured that their........

© The Guardian