He was the author of the Declaration of Independence. He served as the third president of our country. He was an undisputedly important American intellectual and innovator. As we commemorate Thomas Jefferson’s 273rd birthday (he was born on April 13th, 1743), we could certainly remember him for more than one accomplishment.

One could argue that his most lasting impact on the United States, however, was his eloquent defense individual rights. One of the most famous sentences in the English language, penned by Jefferson in the Declaration of Independence, reads:

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.

You have probably heard this before. But how many of us have really pondered these words, can fully explain what unalienable rights are, and can specify who gives them to us? Bridgewater State University Professor Aeon Skoble addresses that question in the video below.

Skoble explains that unalienable—or natural—rights don’t come from anyone, but are part of our very nature as humans. This concept that rights are not granted by a king, a church, or a government was revolutionary during Jefferson’s lifetime and is largely responsible for the United States becoming the freest and most prosperous country in the world.

It’s also perhaps one of the main reasons that Thomas Jefferson’s birthday will continue to be celebrated by those who care about liberty and individual rights for many years to come.