The Doctor squared his shoulders, adjusted numerous subsystems of clothing (today he wore a coat embroidered with flowers, just like the ones painted on his carriage), and walked into the Book-Fair. Jack couldn't see him any more, but he could hear him. Not his voice, actually, but rather the effect that the Doctor's appearance had on the overall sound of the fair. As when a handful of salt is thrown into a pot that's about to boil: a hush, then a deep steady building.