In particular, he allows for blank spaces between features, an 18th-century innovation that meant that the features that were drawn were reliable. Campbell states that Tolkien's mapping style echoes William Morris's Arts and Crafts: "they are functional, but with an eye to grace and beauty", and in her view lie somewhere between illustration and cartography. Tolkien indeed wrote that "there should be picturesque maps, providing more than a mere index to what is said in the text". His maps thus have at least three functions: to help the author construct a consistent plot; to guide the reader; and through the "picturesque", the aesthetic experience, to lead the reader into the imagined secondary world. From map to plot In 1954, Tolkien wrote in a letter to the novelist Naomi Mitchison that Tolkien developed not only maps but names and languages before he arrived at a plot. He had already used Old Norse for the Dwarves of Dale (to the east) in The Hobbit, and he was using modern English for the Hobbits of the Shire (in the west); his choice of Old English for the riders of Rohan implied a linguistic map of Middle-earth, with different peoples, languages and regions. Karen Wynn Fonstad, author of The Atlas of Middle-earth, commented that in such a world, writing has to be based on detailed knowledge of each of many types of details; she found herself, as Tolkien had, unable to proceed with the atlas until she had mastered all of them. Distances travelled, the chronology of the quest, geology, and terrain all needed to be understood to create the work. Impression of depth Campbell stated that the "lovingly detailed" maps helped to shape the stories and create a "believable whole". In Shippey's view, "the names and the maps give Middle-earth that air of solidity and extent both in space and time which its successors [in 20th century fantasy] so conspicuously lack". One way that this works, he argues, is that readers, far from analysing the etymology of place-names as Tolkien habitually did, take them as labels, "as things .. in a very close one-to-one relationship with whatever they label". That in turn makes them "extraordinarily useful to fantasy, weighing it down as they do with repeated implicit assurances of the existence of the things they label, and of course of their nature and history too." Fantasy maps before and after Tolkien Antecedents Tolkien