Today is Constitution Day. It’s not a federal holiday, and that’s fitting. After all, for 225 years now, the Constitution has not taken a day off.

Ours is the longest lasting, most successful constitution in history. But, even this relatively short document contains a few clauses that even seasoned experts forget.

1. Slaves Aren’t in the Constitution, but Pirates Are

When the 13th Amendment was ratified, not a single word of the Constitution needed to be deleted. The word “slave” or “slavery” never appears. In fact, the framers refused to use the words—opting instead for persons held to service or labor—to avoid legitimizing slavery and to emphasize that they were people, not objects.

The Constitution does not classify people according to race, not even in the oft-misunderstood Three-fifths Clause. Free blacks in the North and the South were counted on par with whites for purposes of apportionment. The three-fifths compromise was designed to prevent Southern states from magnifying their political power.

Pirates, however, are in the Constitution. Piracy has long been recognized as an international crime. The Define and Punish Clause (Article I, Section 8 Clause 10) empowers Congress to “define and punish” piracy and other felonies “committed on the high seas.”

2. The Federal Government Isn’t the Only One That’s Limited

In this period of wild federal overreach, many states are eager to push back. That’s a good thing. But the Constitution limits states as well.

Many of the limitations focus on economic powers: states cannot set up artificial barriers to trade by imposing certain taxes, pick winners and losers through contract law, or use Congress to hamper industries in rival states. It is Congress’s duty to lift these barriers to competition and economic freedom. This was the purpose of the Commerce Clause.

3. The Constitution Encourages Swearing

Before entering office, the President swears to “faithfully execute the Office of President of the United States, and will to the best of my Ability, preserve, protect and defend the Constitution of the United States.” But he is not the only member of the federal government to take an oath. Article VI requires members of the legislative, executive, or judicial branches in both the state and federal government to swear to support the Constitution. The first law passed by the first Congress was “an Act to regulate the Time and Matter of administering certain Oaths.”

Why is this significant? Because every government official in every level of government has a duty to uphold the Constitution—from the President and Congress to state governors and legislators.

4. “Rights” Appear Once in the Constitution

Most constitutions around the world enumerate rights: the right to work, to health care, and to ecologically sustainable development and use of natural resources while promoting justifiable economic and social development. In these constitutions, “rights” is just another word for free stuff government gives you.

But in the U.S. Constitution, the government doesn’t distribute rights; it secures them. Therefore, the word “right” is barely mentioned in the Constitution. It appears once in the unamended document: The Patents Clause in Article I, Section 8, Clause 8:“To promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries.” The Bill of Rights further secures rights by limiting the powers of the federal government.

5. A Republic, If You Can Keep It

The Guarantee Clause is perhaps the best—but least-known—clause. It guarantees states a republican form of government where citizens elect representatives who “refine and enlarge the public views” and uphold the rule of law.

More importantly, it protects the states from becoming pure democracies. In a pure democracy there are no intermediate institutions— political parties, representatives, or other constitutional mechanisms—to refine, enlarge, or channel the people’s passions.

There are a few odd clauses and interesting phrases in the Constitution. But there are deeper, more serious constitutional issues to discuss as well: the meaning of the First Amendment, the limits of the Spending Clause, the extent of Congress’s War Powers.

To have these debates and conversations, we need to read, study, and understand the Constitution’s meaning. ConstitutionOnline.com—the only clause-by-clause examination of the Constitution and how it’s been interpreted over the years—is the best place to begin. Let’s start this Constitution Day.