What defines the American spirit?

When I asked for discussion topics, Marica had an interesting idea (Thanks, Marica):

 

One more specific thought along those lines would be quotes– written or spoken– from first generation businessman, of any era, although that may be a bit too specific. Another thought would be discussing what we think defines the American spirit. I’m thinking here of this quote from a piece Andrew McCarthy had up at PJMedia a few days ago.

“One of the many great things about Paul Johnson’s magisterial “http://www.amazon.com/exec/obidos/ASIN/B004IDQRY8/pjmedia-20” A History of the American People is that he begins that history in the Sixteenth Century. There was an identifiable, culturally distinguishable American People long before there was a Revolutionary War, a Constitution, or a central government. The American People, by their industry and ingenuity, didn’t just build successful businesses… they built the most successful nation in history — and all, somehow, without HUD, Fannie, Freddie, the EPA, OSHA… ”
Link:http://pjmedia.com/andrewmccarthy/2012/07/18/you-didnt-build-that-oh-yeah/
So, what defines the American Spirit?