In the early autumn of 2006, while traveling with a friend through Rome, Florence and Siena, and then Venice and its islands, scenes of unusual beauty or character caught my eye: Landscapes and cityscapes in the sunny colors of southern Europe; flower, fish, produce and pastry markets in the city centers; goods on display in shop windows and under rows of tents—and sold by vendors plying the sidewalks and working out of the nooks and crannies of buildings on the streets.