If you've never read any Olaf Stapledon, you've got a real treat in store! As the wiki says "Stapledon's writings directly influenced Arthur C. Clarke, Brian Aldiss, Stanis³aw Lem, C. S. Lewis and John Maynard Smith and indirectly influenced many others, contributing many ideas to the world of science fiction."
My favorite is Sirius: A Fantasy of Love and Discord:
https://www.youtube.com/watch?v=mFNfvDaSh0o
wiki:
http://en.wikipedia.org/wiki/Olaf_Stapledon (http://en.wikipedia.org/wiki/Olaf_Stapledon)
Online collections:
http://olafstapledonarchive.webs.com/ (http://olafstapledonarchive.webs.com/)
http://ebooks.adelaide.edu.au/s/stapledon/olaf/ (http://ebooks.adelaide.edu.au/s/stapledon/olaf/)