Failed to understand the logic about America

The logic about "If its individual citizens, to a man, are to be believed, it always is depressed..." You believe every one of America and America will thus is always depressed? How to understand this logic?

Context:

"If its individual citizens, to a man, are to be believed, it always is depressed, and always is stagnated, and always is at an alarming crisis, and never was otherwise; though as a body, they are ready to make oath upon the Evangelists, at any hour of the day or night, that it is the most thriving and prosperous of all countries on the habitable globe."

More:
http://classiclit.about.com/od/Martin-Chuzzlewit/a/Martin-Chuzzlewit-Quotes.htm