Historian Niall Ferguson discusses his new book The Square and the Tower: Networks and Power, from the Freemasons to Facebook. He tells the story of the fall and rise of networks, and shows how network theory--concepts such as clustering, degrees of separation, weak ties, contagions and phase transitions--can transform our understanding of both the past and the present. Events: Niall Ferguson will be in conversation with Gillian Tett at the New York Public Library (Stephen A. Schwarzman Building) located at 476 Fifth Avenue (42nd St. and Fifth Ave.) on January 17 at 6:30 p.m. and at the New York Historical Society located at 170 Central Park West on January 18 at 6:30 p.m.