From the reviews: "The book under review is a collection of twenty-one survey or expository lectures given by its distinguished author during the period 1943 and 2004 ... . All are (broadly) in the fields of topology, algebra and differential geometry. ... Students will learn an important and substantial swathe of 20th century geometrical mathematics by carefully reading this delightful book." (Ross Geoghegan, Mathematical Reviews, Issue 2008 c) "The papers are arranged chronologically, and cover more than 60 years of work. ... The collection is rounded out by a couple essays on the place of mathematics in culture and its future. ... I heartily recommend adding it to your library." (John McCleary, MAA Online, February, 2009)