This thesis is an edition of John Ruskin's letters to Dr. John Brown of Edinburgh (1810-82), the original MSS. of which are in the Bodleian Library and in the National Library of Scotland. Most of the letters have not been published. Embodied in the thesis is a certain amount of material from the John Brown Papers in the NLS, a mass of letters and other biographical documents recently deposited with the library. The letters of Ruskin are preceded by an Introduction in which Dr. Brown's life and his relationship with his most famous friend are discussed. The letters themselves are given in chronological order, and each letter is followed by notes explaining obscure points and identifying names mentioned. There is one Appendix containing the exchanges in a controversy between Dr. Brown and Forster, Dickens's biographer. The thesis aims to give a readable and informative presentation of previously unknown letters by Ruskin; in these letters, since they are written to a close personal friend, Ruskin's character and the motives of his literary work find clear expression. In the Introduction it is indicated that his public dogmatism was, paradoxically, often the product of a deeply bewildered and injured personality; and that he turned so readily to Brown for friendship because there he found much-needed solace and advice in a harsh world. Dr. Brown is a little-known writer nowadays: some account therefore is given, in the Introduction, of his life and personality, and of the reasons why his contemporaries thought so highly of him - as much for his personal qualities as for his writings. It is hoped that in this thesis some of the beet traits of Ruskin and Brown are preserved.