It is arguably the most important sentence in the Declaration of Independence, and undoubtedly the most famous. But the second sentence of our nation’s founding document may, according to one scholar, contain a significant error in punctuation, at least in the transcript produced by the National Archives and Records Administration. The potential error in question--a period that appears immediately following the phrase “Life, Liberty and the pursuit of Happiness”--may have led to widespread misunderstanding of the Founding Fathers’ intent.

We hold these truths to be self-evident, 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.–”

So goes the beginning of the second sentence of the Declaration of Independence, according to the official transcript produced by the National Archives and Records Administration. But Danielle Allen, professor at the Institute for Advanced Study in Princeton, New Jersey, claims that the period at the end of that phrase almost certainly did not appear on the original parchment version of the declaration, but was mistakenly included in later transcriptions. As the nation prepares to celebrate the anniversary of its independence this July 4th, Allen tells the New York Times that the extra period contributes to a “routine but serious misunderstanding” of the famous document signed by the Second Continental Congress in 1776.

The period at the end of that famous phrase suggests that Jefferson’s list of self-evident truths ends with the pursuit of happiness. In fact, Allen argues, what comes next is equally important: namely, the important role that governments (“deriving their just powers from the consent of the governed”) play in securing these rights. According to her, “The logic of the sentence moves from the value of individual rights to the importance of government as a tool for protecting those rights….You lose that connection when the period gets added.”

Allen began her investigation into this particular punctuation mystery two years ago, while researching material for her book “Our Declaration: A Reading of the Declaration of Independence in Defense of Equality,” which was published last week. She found that the period after “pursuit of Happiness” does not appear on other known versions of the declaration produced and approved by the Congress in 1776, or in most major scholarly works about the document published in the 20th century. After an inquiry directed to the National Archives failed to get a satisfactory answer, Allen turned to various scholars and manuscript experts to help pursue the issue.

The original 1776 parchment of the declaration is credited to Timothy Matlack of Pennsylvania, who served as clerk to the Second Continental Congress, and is housed at the National Archives Museum in Washington, D.C. The parchment has faded so much as to become almost illegible, and scholars have had to turn to other early versions in order to determine the founders’ “original” intent.

The period does appear in some official and unofficial early printings of the declaration, including a broadside, or one-sided newspaper, that Congress commissioned from a Baltimore printer in January 1777 for distribution to the states. Most notably, it appears on a copperplate that engraver William Stone produced in 1823 as an attempt to replicate the original parchment copy. The Stone version is used as the basis for many modern reproductions of the declaration, including the one used by the National Archives.

However, after analyzing more than 70 versions of the Declaration produced between 1776 and 1823, Allen argues that despite subtle variations in punctuation and capitalization, it is clear that the founders did not intend to place a period after “pursuit of Happiness.” She claims that Stone would have found passages in the parchment original unreadable by the time he began his work. In this case, she argues, he would have consulted other versions, including some that included the period. In sum, she concludes that Stone made “an honest mistake.”

The debate may ultimately have to come down to what appears on the parchment original copy of the Declaration of Independence, now badly faded. Some manuscript experts say that in high-resolution images of the document, they can find little evidence of the period in question. James P. McClure, general editor of Thomas Jefferson’s papers, wrote in a memo to the National Archives that the faint mark after “pursuit of Happiness” resembles other marks in the document that are accepted as commas, rather than more definitive periods at the ends of other sentences.

After meeting with Allen last month, representatives from the National Archives say they are considering making changes to the online presentation of the document, and are discussing how best to safely reexamine the parchment original. As William A. Mayer, executive for research services, wrote in an email to the Times: “We want to take advantage of this possible new discovery.” According to Mayer, the staff of the archives is testing the feasibility of using new imaging techniques–including hyperspectral imagery, which collects information from an enormous portion of the electromagnetic spectrum–to capture images through the protective casing over the document. Kept in a bulletproof glass case filled with stabilizing argon gas, the parchment is lowered into an underground vault each night for added security, and was viewed by more than 1 million people last year.