This is the first book in many years to call back to life the correctors of Renaissance Europe. Poor devils of letters, these men (and a few women) marked up copy, divided books into chapters and composed titles for them, and compiled tables of contents before texts went through the press, and read the proofs and corrected them at the other end of the process. Passionately committed to correct and effective usage, they invented the semi-colon and the proof-readers' symbols that are still in use. Those with the greatest reputation for literary taste and skill worked intensively with authors, creating a collaborative form of writing that still persists, in old-fashioned publishing houses at least. To read their letters to authors, to follow their pens as they mark up preserved copy and proofs, and to examine the archival and literary sources that give information about their lives is to see a lost literary world, humble but vital, come back to flickering life.