The Pierpont Morgan Library divides its manuscripts, somewhat arbitrarily, into two principal groups, the “Medieval and Renaissance” and the “Autograph.” Though neither term correctly describes all the materials classified in its group, the division serves well enough to distinguish the handwritten books of the period prior to the spread of printing from the more varied manuscripts of the modern era.

The Morgan “Autographs” comprise the originals of literary and historical writings (with some others of primarily artistic, musical, philosophical, or scientific interest), all letters, and all documents save only those which are in effect illuminated manuscripts. Among these “Autographs” are many manuscripts which are not strictly autograph at all: some are original, though not in the author's hand (Book i of Paradise Lost being an illustrious example of this class, which includes many letters and most documents); others are copies which, for one reason or another, have a particular importance (manuscripts of Crashaw, Sterne, or Keats, for example).