For my birthday, I got a copy (in English) of Isaac Newton's "Principia"...the book everyone is supposed to have read but never has. I am blown away by the first sentence, which is merely a definition of mass. The lucid thinking in this tome is without peer....of course everybody knows this....but this is such a great reminder of where we came from. The things the man did with a protractor and parchment.......I am in awe.