This brief book includes Flexner’s timeless 1939 essay alongside a new companion essay by Robbert Dijkgraaf, the Institute for Advanced Study’s current director, in which he shows that Flexner’s defense of the value of “the unobstructed pursuit of useless knowledge” may be even more relevant today than it was in the early twentieth century. Dijkgraaf describes how basic research has led to major transformations in the past century and explains why it is an essential precondition of innovation and the first step in social and cultural change. He makes the case that society can achieve deeper understanding and practical progress today and tomorrow only by truly valuing and substantially funding the curiosity-driven “pursuit of useless knowledge” in both the sciences and the humanities.