“One of the world’s rarest books — a belligerent 42-page rant written, published and signed by Galileo in 1607 — is likely to be the star of the Antiquarian Book Fair at Olympia in London next month,” reports Nigel Reynolds in a story for The Daily Telegraph. “Galileo wrote La Difesa (The Defence) to attack a scientific rival, Baldessar Capra,” notes Reynolds. “Both men had claimed to have invented a hand-held mechanical calculator, Il Compasso, which was to be a precursor of the slide rule.” Only about 12 copies are thought to be in existence. ” In the atmosphere of suspicion, rivalry and Church persecution that pervaded the city in the early 17th century, dignatories who had been presented with copies very probably obliterated Galileo’s signature because he was dangerous to know,” says Reynolds. Asking price of this copy: £500,000.