Book excerpt: "Between the invention of photography in 1839 and the end of the nineteenth century, portraiture became one of the most popular and common art forms in the United States. ... images of human surfaces became understood as expressions of human depth during this era. Combining visual theory, literary close reading, and in-depth archival research, Blackwood examines portraiture's changing symbolic and aesthetic practices, from daguerreotype to X-ray. Considering painting, photography, illustration, and other visual forms alongside literary and cultural representations of portrait making and viewing, Blackwood argues that portraiture was a provocative art form used by writers, artists, and early psychologists to imagine selfhood as hidden, deep, and in need of revelation, ideas that were then taken up by the developing discipline of psychology"--