This is the book that kickstarted it all for me. I had the wrong attitude to truth before I read this. Dawkins acheived so much in this work. A new (and logical and true) perspective on our evolutionary origins was presented (mainly using the work of William Hamilton, I think, to put group selection theories in their place). It was presented in a readable way, thus a coming-of-age for the Pop Science genre. It established him as the prime-mover in modern British culture for rational discourse (he's amazingly rigorous in his thoughts, his famous letter to his ten-year-old daughter on the subject of Truth & good criteria for believing in things should be read in school assemblies every thursday, fo' sho'). And he set out a rough theory of memes (cultural darwinism), which also paved the way for much edifying discourse on Universal Darwinism. He's the man.

This is one of the best books I've ever read. It's not easy, but it's amazingly rich, beautiful and strangely funny. It's about the relationships between people and objects in this crazy modern world of ours (well, circa 1960). The man is a genius.