“I am a BRITON,” Benjamin Franklin declared proudly and in capital letters. If that sounds a bit odd coming from the man whose face now adorns the $100 bill, you have to consider the times. It was 1763, and Great Britain had just won a long war against France for dominance in North America, a victory which, historian John Ferling writes, “quickened the colonists’ pride in being part of such a great and noble empire, one with a reputation for being the most religiously tolerant and enlightened of the great powers.” Yet only 13 years later, Ben Franklin and many of his compatriots were in open rebellion against this same benignant empire, and they weren’t calling themselves Britons anymore. They had become Americans, in many cases with a vengeance.

The anger that took hold in those years can be difficult to understand today, as it was even then to a sizable part of the American population. It stemmed above all from taxes of various kinds (the war had to be paid for), and also from trade restrictions by the mother country, and from British policies that frustrated ambitious, expansionist colonials. And liberty was in the air, fostered by British political philosophers and other figures of the European Enlightenment as well as homegrown agitators who talked boldly of republican government.

When the war came, the moral arguments weren’t all on one side. One action that triggered fury in the southern colonies was Britain’s offer to give freedom to slaves who fought on the British side. But on July 2, 1776, when the Continental Congress voted for independence, it wasn’t in a position to be too evenhanded; the Declaration was to be a justification for the break, heavy on grievances.

John Adams, who had introduced the motion for independence, didn’t have time to write it and assigned the task to Thomas Jefferson. Mr. Adams “never imagined that anyone would remember the Declaration of Independence,” writes Mr. Ferling. Even someone as astute as Mr. Adams could hardly have foreseen the mystical and enduring power of words in a republic that came to see itself as founded upon them. The most stirring words in the Declaration that was adopted by the Congress on July 4 are of course its statement of the “self-evident” truths “that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness.” But these truths clearly weren’t evident to hundreds of thousands of enslaved people from Africa, and in less than a century the new country was torn apart by a contradiction that could no longer be ignored.

The power of words was illustrated again last week in the Supreme Court’s decision on the constitutionality of the health-care act. In the past two centuries, written constitutions have sprouted all over the globe, and in far too many cases they sound good and mean nothing. (“The state is at the people’s service.” — Article 12 of the Syrian Constitution.) No matter what one might think of the outcome of the health-care case, the spectacle of crowds demonstrating, judges arguing and the people and media going at one another furiously over the meaning of a brief passage in a document written more than 200 years ago makes for a pretty good show. Let the fireworks continue.