Gazing out over the soaring Manhattan skyline with the warm afternoon sunlight streaming into the office, Prosper and Martine Assouline are like a tale of two cities. Prosper is a bundle of restless energy, chatting avidly, while Martine has a poised Parisienne elegance. Together, the co-founders of Assouline Publishing exude warmth and wit, with a joie de vivre that is all-encompassing.