Any reasonably complete history of scientific cosmology, whether or not it specifically aims to shed light on the multiverse concept as this book does, is bound to spend much of its time on ancient and (especially) medieval ideas that were hopelessly entangled with religion. So it is that at least a third of Siegfried's volume is riddled with tiresome god-talk. But this annoyance is well compensated for by the late chapters, which include coverage of the quantum many-worlds, the chaotic-inflation, the stringy-"landscape", and the "braneworld" varieties of multiverse. It all adds up to a strong case against those who maintain that the multiverse idea is not science.