Anathem 
 Neal Stephenson's latest brick of a novel is both something of a departure for him, and carries on in what he has made his own inimitable style. The newness comes in the fact that this is the first 'real' science fiction novel he has written - in that it deals with space travel and alien worlds, although he of course began his career with cyberpunk in Snow Crash and the wonderful view of how technology shapes the mores of a future society in The Diamond Age. However, Anathem very much continues what he has made his own style over his previous four novels - Cryptonomicon, and the Baroque Cycle trilogy. Each of these volumes weighs in at around a thousand pages and combines high adventure with discussions and explanations of profound mathematical and philosophical concepts, including endnotes and diagrams, but are surprisingly easy reads, thanks largely to Stephenson's wonderful clarity and openness of style. 
 Anathem takes place on a world where the educated elite live apart from the general population in monastic-style communities which live with only basic technology and shut themselves off from the outside world for at least a year at a time - or ten, a hundred or a thousand years for parts of the communities, accepting new recruits rarely and not communicating with the outside world. This allows them to avoid 'contamination' from transient agencies such as popular culture or politics but is also, it becomes apparent, something that was enforced on them in the past when the general population became afraid of technologies these thinkers were developing. However, when an alien threat to the whole world appears, the old order becomes threatened and the monastic and 'secular' sides of the world have to cooperate. 
 The first thing that grabbed me about the novel is the way in which Stephenson uses language; there is a 'note to the reader' before the main text explaining the origin of the word Anathem - a pun on anthem (a piece of music) and anathema (an object of hatred) to mean a ritual enacted when a thinker is expelled - and that he derives much of the archaic-sounding language of the maths (as the 'monasteries' are called) in a similar way. Much speculative fiction uses strange words to demonstrate an alien culture, and this method is wonderful; the reader quickly becomes accustomed to the mode of speech, and when you can't figure out what the words mean from context and etymology there's a handy glossary. 
 There is a superb sense of the 7000 years of history and knowledge that the cloisters are protecting, in the language their and the traditions; the rituals for welcoming new entrants or expelling wrongdoers, songs in which the harmonics are the expression of mathematical equations. The author often explains ideas to the reader by the simple but effective method of having them explained to a character, in the manner of true Socratic dialogues, which is not nearly so clumsy as it sounds and is vital considering the weight of some of the ideas that he throws around. For instance, this book has left me intent on reading up on Phase Space and the in particular how it relates to parallel universes. 
 The one thing that lets the book down, and kept it from a five-star rating, is the adventure side. In his previous books these have been genuinely thrilling, but in Anathem there are a couple of frankly dull picaresque sections, notably the travel over the north pole. The only reason I can think that this is so is that both Crytonomicon and the Baroque Cycle were set in our own past (World War 2 and the late 17th/early 18th centuries respectively), and so more energy is spent on creating the imaginary world than the events of the journey. 
 Everything else, though, works. The relationships between knowledge, politics and religion; scientists responsibility to the wider world, and the world toward scientific endeavour; love, loss and the possibilities of multi-dimensional reality. As always, Neal Stephenson is a wonderful writer for expanding the horizons, inside and out.