The Cotton Genesis is one of the great treasures of the British Library. Created probably in Egypt in the 5th or 6th century, it is a manuscript of the Book of Genesis in Greek accompanied by large illuminations, depicting scenes from the biblical text. It originally contained over 300 illustrations, and is valuable evidence for the history of book illumination in late antiquity. Unfortunately, the manuscript was badly damaged in the Ashburnham House Fire of 1731. At this time, the entire Cotton Library was stored in Ashburnham House, and many volumes were damaged or destroyed during the fire. The heat caused many of the leaves of the Cotton Genesis to shrink, and much of the surviving decoration is badly discoloured. Nonetheless, enough survives to make it clear that the volume was once one of the finest illuminated manuscripts in existence. Indeed, it was the favourite manuscript of Sir Robert Cotton himself.

The manuscript was presented to Henry VIII in the 16th century, and passed by descent to Elizabeth I. It subsequently came into the possession of Sir Robert Cotton (1571–1631). Cotton’s vast collection of manuscripts was augmented by his son, Sir Thomas Cotton (1594–1662), and grandson, Sir John Cotton (1621–1702), who bequeathed the collection to the nation. The Cotton library subsequently formed one of the foundation collections of the British Museum in 1753.