What two centeries were the centeries of philosphers

As question is raised in a U.S. history classThe Founders were very influenced by Locke's "Two Treatises of Government," written about 120 years before Jefferson wrote the "Declaration." Hobbes' work was also written in the 17th century, and is likewise of interest. 

And then there's the 19th century, of American thinkers, such as Emerson, William James, and Charles Peirce (pronounced "purse"). 

Then, there's the 18th century, but if influences are calibrated, Locke in the 17th, and Emerson and James in the 19th