I think he is that because in the passage he states about how he believes that the power to rule should lay with the people. He also believes that no one should get special treatment because of birth or fortune.
Though the Declaration of Independence is not a binding legal document it did eloquently express the ideals of the new country, one of which was that the people control the government. This principle of<em> limited government</em> was later incorporated into the Constitution.
In my view the period that has had the biggest impact on the development of US society is The Great Depression. That depression brought a huge economic growth but also changed mass culture that swept many Americans into consumer society.