I finished A Short History of Nearly Everything by Bill Bryson this weekend. Bryson has plenty of cool analogies and funny anecdotes, but the book is enjoyable because he tells a story. He starts with the beginning of the universe and ends with the evolution of man. I've never read a more witty, readable, and interesting book that covers so many topics.
I learned that humans, and our history as a civilization in particular, are so tiny and insignificant in the larger picture of life and space that it's beyond our comprehension how small and ephemeral we are. We are not the culmination of anything and one day we won't be at all. All species become extinct eventually. We're a brief success in a period of good weather between ice ages.
Sooner or later another ice age will come, an asteroid will hit the Earth, the volcano underneath Yellowstone will explode or any other number of cataclysmic events will push the reset button. It's not something to stay home and hide under the bed over, but the Earth is always changing and it's not going to stop just because we have TiVo and Newlyweds.
We're tiny and that's the way it is.