This first book in Stephenson's "Baroque" cycle starts brilliantly, timehopping chapters introducing a complex brew of early science, religious descent and dynastic politics in late 17th England. Things go horribly downhill in the middle section with the introduction of two very annoying characters, Jack the Vagabond and Eliza, the slave-girl he rescues from the siege of Vienna. Jack's only there to set up implausible comedy-action setpieces which might work in a movie but fall flat on the page. Eliza's role is to meet all the major characters in the book and write them interminable letters updating them on the plot. Not that it's clear that there is a plot, but the book marches happily along to the drumbeat of 17th century history, and there's two more books for Stephenson to work out his grand design. It all passes the time agreeably enough, particularly once you learn to skim read anything involving Jack and Eliza. Not one for the fan of the traditional historical novel, nor if you're expecting the depth of Barthes or Pynchon. But if you like to see a science fiction sensibility brought to bear on an era when science itself was more imagination than dogma, then this is for you.