Prior to William Blades’s Life and Typography of William Caxton in 1861-1863, the answer to the question “what is [a] Caxton?” would have been easy: the question concerned material books known as “Caxtons”—the surviving products of the press of William Caxton. They were first of all valuable artworks, often set in the modern binding frames characteristic of aristocratic collectors. In addition, these objects served as an index of printing history; they were both artistic monuments and documents attesting to the history of English printing and by implication English culture. When the Earl of Pembroke collected such a Caxton, it was shelved under “early printing,” a section of his library separate from the section “early editions of the classics.” A composite volume once owned by John Moore, Bishop of Ely, originally contained several pamphlets printed by Wynkyn de Worde and Richard Pynson; the addition of a Caxton to this volume in the early eighteenth century transformed it into a material icon of early English printing history.1