This is a beautiful book, to be read by everyone who is fascinated by the ongoing quest to unify cosmology and particle physics. The author has a cute idea - that the familiar multiple universes undergo a process of evolution and natural selection - but he goes much further, into the philosophical foundations of quantum theory and the basic notions of space and time. I particularly enjoyed (and found convincing) his claim that we are living in a period, analogous to the early years of this century, when the shared ideas that have been so productive, have become inadequate. A new paradigm is needed, according to Smolin, one that takes into account the self-organizing properties of the Universe, and the inter-relationships between all of its components. One doesn't have to agree with the author to appreciate the originality of his ideas, the clarity of his arguments (masterful explanation of black holes, for instance) and his candid description of his own struggle to break away from conventional thinking about fundamental physics issues. Smolin thinks big, but he is not afraid to admit that his theories are not fully worked out, and that many scientists object to his ideas (I, for one, could not follow his rejection of fixed external physical laws, when his theory of incrementally evolving Universes seems to require just that). But no matter - anyone who wants to appreciate (without math!) what is really happening on the frontiers of physics should read this book. One gripe: the book is set in a font so tiny that it's almost unreadable.