S&T Chapter 8 I think: Carl Sagan.

Carl Sagan has been dead for around 15 years, but it is just recently that I have started to listen / watch videos of him, and red books / articles that he wrote. He is one of the most humble / logical people I have ever seen / heard of. Honestly, I'm sure a lot of people probably will find him boring, so, to save you getting bored, watch this 3 minute video of him instead of the hours of video / hundreds of pages. For those who don't know, Carl Sagan was an Astrologist by trade, but he traveled far beyond just being a simple astrologist.

Here is one short video that I like: http://www.youtube.com/watch?v=gCfemmxqaRg

or the Nasa "Commercial" I guess you could call it, is another great short one:

http://www.youtube.com/watch?v=oY59wZdCDo0