Fox News contributor Jonathan Turley previews his book on the threats to free speech on 'Special Report.'

For many of us, the Fourth of July is a favorite holiday as families gather around barbecues and picnic blankets to this quintessential American experience. Yet, in the midst of the food, fireworks and friends, it is also a holiday to reflect, if only briefly, on what brings us to this moment each year in celebration of the Declaration of Independence.

This year, the holiday seems even more important. The core values that define us as a people are again under attack, particularly the right that defines us as a people: free speech.

In my book, "The Indispensable Right: Free Speech in an Age of Rage," I discuss our struggle with free speech through the stories of the heroes and villains of our Republic. Two of those figures, John Adams and Thomas Jefferson, also happened to die on this date.

Thomas Jefferson, left, defeated President John Adams in the bitterly divisive election of 1800. They were allies in the cause of liberty and political enemies in the new nation, but developed a warm friendship in later life. (Kean Collection/Getty Images | Smith Collection/Gado/Getty Images)

Adams and Jefferson were fierce political enemies who would rekindle their friendship in their final years before they both died on the very same day, July 4, 1826. Jefferson died first at Monticello, Virginia, around noon, He was 83. A few hours later (without knowing of his friend's death), Adams passed away in Quincy, Massachusetts, at the age of 90.

AGE OF RAGE VS. FREE SPEECH: WE'VE BEEN HERE BEFORE AND HERE'S WHAT HAPPENED

In his 1826 eulogy for both men, Daniel Webster (like many in........

© Fox News