Harley's importance to literature cannot be overstated. As a patron of the arts, he was notable. As a preservationist, he was invaluable. He used his wealth and power to collect an unparalleled library. He commissioned the creation of ballad collections, such as The Bagford Ballads, and he purchased loose poems from all corners. He preserved Renaissance literature (particularly poetry), Anglo-Saxon literature that was then incomprehensible, and a great deal of Middle English literature. His collection, with that of his son Edward, 2nd Lord Oxford and Mortimer, was sold to Parliament in 1753 for the British Museum by the Countess of Oxford and Countess Mortimer and her daughter, the Duchess of Portland; it is known as the Harley Collection.