Though perhaps best known for his portraits, American painter Abbott Handerson Thayer (1849-1921) also developed detailed theories of animal camouflage. With his fine-arts training and his careful observations of nature, Thayer created works that he believed argued for his views on natural selection. He later patented his camouflage patterns and lobbied the US military for the use of his designs on ships and uniforms; his theories were eventually published in 1909 and were hotly debated by leading scholars and public figures of the day, including Theodore Roosevelt. This book is the first to address Thayer's participation in some of the greatest scientific and cultural debates of his age, proposing that the artist's seemingly idiosyncratic religious subjects and scientific theories were an attempt to reconcile spiritual uncertainties in a time of emerging science. The new scholarship lends insight into an Anglo-American culture unmoored by Darwinism and the horrors of World War I.