A woman who has cherished a viper in her breast might be expected to speak with a note of asperity. There is a tinge of this in Jane Hawking's account of the end of her marriage to the super-brilliant scientist, Stephen, whose A Brief History of Time sits on a million bookshelves. However I suspect Mrs Hawking always spoke a bit like Joyce Grenfell, in the clipped syntax of the well-educated middle class from which she sprang, with an inherent love of classical music and philosophy. Her story - which tells how Stephen, who suffers from motor neurone disease, fell in love with one of the nurses employed to ease the burden of 24-hour care on his family - is an ironic one; but at around 600 pages is perhaps a little more than we want to know about a marriage that ran aground, even if one of the great contemporary geniuses, and one with a crippling disease, is involved. One interesting point: being a genius didn't help Hawking get a motorised wheelchair out of the National Health Service.