When July 4 rolls around, there’s no mistaking it. There are fireworks, parades and other patriotic tributes to our Declaration of Independence. If you’re like most Americans, Sept. 17 comes and goes without any fanfare.

It’s a shame, really. Constitution Day may lack the flair and pageantry of our national birthday, but without this landmark document that carefully outlined the form of our republic, it’s unlikely we’d still be celebrating the declaration in the 21st century.

How can we make sense of our history without a proper understanding of the Constitution? How can we know, for example, why President Lincoln was willing to endure a bloody civil war (one that came perilously close to costing him re-election in 1864) to preserve the union if we don’t know how that union works and how it was formed?

For that matter, good luck making sense out of the cases heard by the U.S. Supreme Court and various appellate courts every year without an understanding of the Constitution. If you don’t know what it permits and what it doesn’t, an informed opinion about the decisions they reach is impossible.

So many government agencies make decisions every day that affect our lives. How can we know if they are acting within the law – or if they are pushing the limits, as those who are entrusted with power so often do – if the Constitution is unfamiliar to us?

There’s a reason our Constitution has endured for so long. Few of them do.

According to Thomas Ginsburg, Zachary Elkins and James Melton, authors of “The Lifespan of Written Constitutions,” the average life span of a constitution since 1789 is only 17 years.

Some don’t even get halfway to that mark. Messrs. Ginsburg, Elkins and Melton quote an old joke: A man goes into a library and asks for a copy of the French Constitution, only to be told the library doesn’t stock periodicals.

So, for a constitution to last more than two centuries – through wars small and big, through periods of great transformation and upheaval – is a remarkable achievement. No wonder William Gladstone, the legendary British prime minister, called the U.S. Constitution “the most wonderful work ever struck off at a given time by the brain and purpose of man.”

If you’ve never read it – or if the last time you did is years ago, when you were cramming for an exam – I’d like to encourage you to do so. It’s not nearly as daunting a task as some people may assume. It’s about 4,500 words or so, and it takes roughly half an hour to read it. It’s more accessible than you may think.

To really understand it, though, a little help is in order. That’s why the Heritage Foundation first published “The Heritage Guide to the Constitution” in 2005, and why we’ve now issued a revised edition, complete with expert analysis of every single clause. It has relevant court cases, a rundown of the various interpretations that have marked our constitutional history, and an overview of the Constitution’s creation.

You can see why the guide is used by law schools nationwide. It’s just as handy for any citizen who wants to understand the law of the land. Whether you’re writing a complex thesis or simply typing out a quick letter to the editor, the Heritage guide can help.

“It is our fundamental law because it represents the settled and deliberate will of the people, against which the actions of government officials must be squared,” writes former U.S. Attorney General Edwin Meese III in the guide. “In the end, the continued success and viability of our democratic Republic depends on our fidelity to, and the faithful exposition and interpretation of, this Constitution, our great charter of liberty.”

Something to think about the next time Sept. 17 rolls around.