'The Pope's artillery, then, breached the walls in several places – creating spills of rock across the dry-moat. White mortar clings to the dark stones like shards of bleached bone. Then fire burnt out the insides, and took all but a few blackened rafters from the roof – all the windows and gun-ports have spreading smoke-stains above them, as if flames jetted from those openings for hours – it is like an Alchemist's furnace in which a whole town was purified of heresy.'