Thomas Paine's "Common Sense" was one of the major factors in bringing about the American Revolution. The main thesis or central message of the book was A) that monarchy was a bad form of government and B) that the American colonies should become free from England and form their own country.
Before Paine wrote this pamphlet, the idea of rebelling against England was not very strong in the colonies. Neither was the idea that monarchy should be abolished. Instead, most people wanted to remain part of Britain, under the king, but with better laws and a bit more self-government. Paine's writing convinced large numbers of Americans that it would be better to be independent and to no longer have a king.
It basically means its the right thing to break away from Britian.