A passionate advocate of evolutionary theory, Gould wrote prolifically on the subject, trying to communicate his understanding of contemporary evolutionary biology to a wide audience. A recurring theme in his writings is the history and development of pre-evolutionary and evolutionary thought. He was also an enthusiastic baseball fan and sabermetrician (analyst of baseball statistics), and made frequent reference to the sport in his essays. Many of his baseball essays were anthologized in his posthumously published book "Triumph and Tragedy in Mudville" (2003).