Those who read with pen in hand form a species nearly extinct. Those who read the marginal notes of readers past form a group even smaller. Yet when we write in antiphonal chorus to what we’re reading, we engage in that conversation time and distance otherwise make impossible. Coleridge, one of the most obsessive of marginal annotators, those graffiti artists of the book, was so addicted to the practice that any book borrowed became a hostage to fortune. If he ever managed to return it, the margins were likely to be heavily defaced—he crowded his arguments into the forum of the side aisles.

Before the middle of the nineteenth century, reading in this wrangling or reciprocal manner required more preparation—your quills, your knife to sharpen those former pinions, and your pot of ink (India) had to come ready to hand. You needed a flat place to lay these furnishings—a ...