Though life’s ultimate meaning may be elusive, the goods of love, work and play are so deeply rewarding that for most people they are sufficient for creating a happy life. And with new advances in neuroscience, we increasingly understand why that is at a molecular level.  GUEST Paul Thagard is a philosopher, cognitive scientist, and author of many interdisciplinary books. He is Distinguished Professor Emeritus of Philosophy at the University of Waterloo, where he founded and directed the Cognitive Science Program.