This is a long text—a book really—much of which would be more appropriate for a philosophy course. Don't worry—you don't really need to know everything he says in it right now.

Locke's theory on government, though, was hugely influential in the 18th century, and is directly referenced in the Declaration of Independence…as well as other documents supporting American independence.

Ideas about government that we take for granted nowadays emerged during the Enlightenment, a period of philosophical revolution in Europe. The prominent Enlightenment thinkers were studied by the Founding Fathers, and their ideas made people around the world start to question the established order of human society.

Locke's primary philosophical legacy is the idea of a contract between a government and its people. He claimed, contrary to what others had argued previously, that government was an institution created by the people for their own safety. Humans gave up some, but not all, of their freedoms for the protection and care of a government of their own design, and in return the government is responsible for upholding its purpose of caring for the people's welfare. (Source)

Locke also discusses people's right to private property (woo-hoo!) which had a similarly lasting influence on political philosophy.

Some of Locke's ideas may sound super familiar. For instance: "reason...teaches all mankind, who will but consult it, that being all equal and independent, no one ought to harm another in his life, health, liberty, or possessions." (Source)

Hmm. Sounds a lot like "life, liberty, and the pursuit of Happiness," doesn't it? Locke said it eighty years earlier, though.

Locke also asserted that people were born equal in a nature, which of course sounds an awful lot like "all men are created equal." In fact, someone has kindly outlined some of the influences of the Second Treatise of Government on the Declaration of Independence here.

The book contains a lot more than the strikingly similar-to-the-Constitution passages, and has chapters on the nature of war, slavery, property, and "paternal power" (relationships between spouses and family members), as well as several sections on government and civil society. Locke's concept of government being responsible to the people, though, is the most powerful and influential legacy of his in American politics, not to mention in nations around the world.

As smart as the Founding Fathers were, the ideas and language used by Jefferson, Adams, and other revolutionary leaders didn't come out of nowhere, it was a continuation of political ideas going back to the Enlightenment.

Thomas Edison famously said that "Genius is one percent inspiration, ninety-nine percent perspiration," but in this case the inspiration percentage might be slightly higher. Although, to be honest, Jefferson could have been incredibly sweaty…there's really no way to know.