Well, this was the book containing the lecture series Feynman gave as a university professor. The reason I chose it is that I think that he is one of the most intelligent people to live in the 20th century. Yet at the same time, surprisingly, he is an amazingly good teacher. The area Feynman was really involved in was quantum physics. At the time he was writing there was this sudden realisation that the very small scale was going to have to be married up with the huge scale (what we thought we knew already).