In this lecture originally presented on November 20, 2013, speaker Jennifer L. Roberts of Harvard University explores one of the fundamental operations of printmaking—reversal—in order to trace its impact on American art across a spectrum of media. Behind every print lies a matrix (from the Latin for mother): a plate or block or stone or screen from which the print has been "pulled." And in most printing processes, the final print is a reversed version of the matrix. Although reversal may seem at first to be a simple geometrical switching operation, its material and philosophical complexity is profound; indeed, one may posit a kind of "negative intelligence" that informs any work of art that deploys reversal. To focus on reversal is to open up new ways of thinking about connections among the fine, decorative, and industrial arts in America, not least because so many prominent American artists from the 18th through the 20th century had backgrounds in print and printmaking. "Apprenticed as an engraver"; "trained as a lithographer"; "found initial success as a commercial artist": such are the typical preludes of American artists' biographies. A rigorous analysis of reversal offers an opportunity to expand the adventure of print from the preludes into the main narratives of the stories we tell about American art. The lecture addresses reversal in several contexts, from the nature prints of Joseph Breintnall in the 1730s to the handprints of Jasper Johns in the 1960s, with a core focus on the later 19th century in the work of James McNeill Whistler and the American trompe-l'oeil painters.