I had certainly heard of Carl Sagan, but only in terms of cosmology. I had no idea that he wrote extensively on the field of evolutionary biology-stimulated by his wife, the biologist Ann Druyan. My field is not science, so The Dragon's of Eden was my first encounter with the idea of the tripartite brain. The idea does not originate with Sagan, as he himself points out, but this slender volume makes the idea quite assessable for the lay person and, more importantly, it creatively explores the idea's possible implications. Although I read this book years ago, I have thought of it several times a week since then, as I speculate upon some of the biological causes of human behavior. Newer models of the brain have already proved some of the basic ideas in this book as a bit oversimplified, but if you are looking for an introduction to speculating about how the brain's evolution may shape human behaviors, this is great place to start. I found the book a "mind blower"-and I always pick it up used when I see it to give to friends. Prepare to have your perception of perception itself turned upside down.