Perhaps the most peculiar thing about the Declaration of Independence is that the portion of it that seemed commonplace when it was written now seems revolutionary, and the part that seemed to its framers as most central, to us seems trivial, even whiny.

As a piece of rhetoric, it begins in generalities, narrows to specifics, and ends in a course of action. It couldn’t be more concisely structured. The committee charged with drafting it in the summer of 1776 chose wisely when it asked Thomas Jefferson to write the first version. Jefferson’s prose is a model of late 18th-century style: precise, lucid and syllogistic.

But the only part of the Declaration that most people can recall, outside the opening, “When in the course of human events,” is the second paragraph. That second stanza contains the seed of every revolution that followed, from the bloody French to the bloody Russian. It is a statement of belief that is the foundation of American society, and almost every government created since 1776.

It states baldly and without argument or support, that all men are born equal, have certain rights by virtue solely of being born, and that when a government fails egregiously to effect the safety and happiness of the people, it is their right to replace it.

But Jefferson didn’t invent its ideas whole cloth. In fact, as Jefferson wrote years later, the purpose of his stirring words was “not to find out new principles, or new arguments, never before thought of, but to place before mankind the common sense of the subject, in terms so plain and firm as to command their assent, and to justify ourselves in the independent stand we are compelled to take.”

Much of the remainder of the Declaration is given over to a litany of complaints the colonies had about British governance. Some of these complaints still seem legitimate; many seem trivial, even trumped up. “The King did this” and “The King did that.” ”

He has plundered our seas, ravaged our coasts, burnt our towns and destroyed the lives of our people,” it says. Pure hyperbole.

These complaints were the part of the Declaration that was “news” in 1776. They constituted what made the document inflammatory.

Few can read through the whole of the Declaration of Independence now without a sense of fatigue: Those complaints were the issues of 1776, not of today.

It is the second paragraph that seems told to all people at all times, and remains news to us in the 21st century.

Bridge between ages

But to follow those ideas from the century before the Declaration into the ink on its page shows just how important its year of birth was. It was born in the cusp between two great ages, two overriding sensibilities, and partakes of both.

The period from about 1750 to about 1825 is one of the richest in humankind’s history, fertile, even febrile. It is in many ways, the hinge between the past and the modern, between the classically minded 18th century and the Romantic 19th. From an age of Reason to one of Sentiment — as it was called at the time. In Europe, it was the age of Goethe and Rousseau.

And no figure in the American experiment better demonstrates that shift of sensibilities than Jefferson.

On one hand, he epitomized the faith in science and logic of the Enlightenment; on the other, he shared with the revolutionary Rousseau the belief in the nobility of humanity and its drive to social improvement.

You can hardly fail to notice this point when you visit Jefferson’s home in Virginia.

Monticello is a mirror of its maker. Jefferson built a model of Palladian proportion and filled it with moose antlers. The outside lines of the house are clean and mathematically rational. The inside is a warren of peculiar and unnerving spaces.

Jefferson never fully reconciled these two aspects of his personality. He was a slave owner who sings of the dignity of the free man. How much more conflicted than that can you be?

The Declaration of Independence speaks to us now, in large part, because of this clash of sensibilities in Jefferson.

On the one hand, you have the ideas of the Enlightenment, that brilliant flame of philosophy and science that sprang up in Europe in the 17th and 18th centuries.

On the other hand, you have the growth of the individual as a thinking and feeling person.

The Enlightenment preached rationality and temperance, tolerance and universal principals. One of its most influential writers was John Locke, who, in his Second Treatise on Civil Government, from 1690, wrote that all human beings have natural rights and that these included “life, liberty and the pursuit of property.”

It was an idea that took hold and flourished.

By the time of the American Revolution, the idea was commonplace. It shows up in George Mason’s Virginia Declaration of Rights in June 1776, in slightly altered form:

“That all men are by nature equally free and independent and have certain inherent rights, of which, when they enter into a state of society, they cannot by any compact, deprive or divest their posterity; namely, the enjoyment of life and liberty, with the means of acquiring and possessing property, and pursuing and obtaining happiness and safety.”

When you compare that with what Jefferson first wrote, you can see how much better a writer Jefferson was. He only needed 31 words to say what Mason required 57 for, and say it more forcefully and memorably.

An economy of words

Jefferson’s first take on this was considerably more sonorous, but still not quite there:

“We hold these truths to be sacred, that all men are endowed by their Creator with certain unalienable rights, and that among these are life, liberty and the pursuit of property.”

It was a committee of five, delegated by the Second Continental Congress, that were given the responsibility to draw up the Declaration. Jefferson wrote that first draft, but Benjamin Franklin, also on the committee, struck out “sacred” and replaced it with “self-evident.”

By 18th-century reasoning, self-evidence was universal, while sacredness could be construed as sectarian. Franklin wanted to emphasize the universal truth of the proposition.

And Jefferson himself changed “property” to “happiness,” and with that stroke made the Declaration jump from the past into the future.

The past was Thomas Hobbes, with his sense of the nastiness, brutishness and shortness of life, and a belief that the natural order of mankind was greed, rapine and thievery. Only strong central government, he wrote, could possibly control the natural impulses of humankind.

The future was Rousseau’s perfectibility of man, his belief in the nobility of those uncorrupted by society and government, the “natural man.”

The middle was Jefferson, perfectly if perilously balanced between.

The right of life remained pretty much the same looking forward and back, but the other two rights changed meaning over the cusp of 1800.

Locke believed that all humans coveted was property; Jefferson realized that there were many routes besides ownership to humanity’s true goal, individual happiness. Hence, the change in language.

Liberty is the word that has changed the most. In the 18th century, it meant being left alone, basically. Your government let you be: Taxes shouldn’t be too onerous and armies shouldn’t be quartered in your home at the whim of the commandant.

But by the 19th century, liberty took on a more revolutionary turn: Romantic writers saw liberty as the antidote to repressive regimes around the world and one read poems to Count Egmont, the Prisoner of Chillon and Nat Turner. It fueled popular movements all across Europe and led to a crisis year in 1848. Liberty meant revolt — a very different thing from what John Locke had in mind.

(And it makes almost comic the confusion of the two versions of liberty conflated by contemporary anti-tax factions and the paranoid fringe looking for the black helicopters that we can get all belligerent and militant about “tyranny” in Washington, when compared to what is happening in Sudan, Russia or North Korea, we remain among the most liberty-ridden people on earth. Admittedly, the Declaration of Independence itself is full of the same sort of inflated rhetoric.)

“Life, liberty and the pursuit of happiness.”

This meant that the Declaration could speak, Janus-like, forward and backward. The fulcrum of modern history. The Enlightenment is emerging from its chrysalis into the age of Romanticism.