INTRODUCTION. Sir Walter Scott's "Letters on Demonology and Witchcraft" were his contribution to a series of books, published by John Murray, which appeared between the years 1829 and 1847, and formed a collection of eighty volumes known as "Murray's Family Library." The series was planned to secure a wide diffusion of good literature in cheap five-shilling volumes, and Scott's "Letters," written and published in 1830, formed one of the earlier books in the collection. The Society for the Diffusion of Useful Knowledge had been founded in the autumn of 1826, and Charles Knight, who had then conceived a plan of a National Library, was entrusted, in July, 1827, with the superintendence of its publications. Its first treatises appeared in sixpenny numbers, once a fortnight. Its "British Almanac" and "Companion to the Almanac" first appeared at the beginning of 1829. Charles Knight started also in that year his own "Library of Entertaining Knowledge." John Murray's "Family Library" was then begun, and in the spring of 1832—the year of the Reform Bill—the advance of civilization by the diffusion of good literature, through cheap journals as well as cheap books, was sought by the establishment of"Chambers's Edinburgh Journal" in the North, and in London of "The Penny Magazine."