The author of The Princess and Curdie, George MacDonald, passed away when Tolkien was 13, an age at which the latter would have first been introduced to MacDonald's fairy tales. 

Professor J.R.R. Tolkien, as he later became, was greatly influenced by George MacDonald’s vivid imagery and world-building in a way that left a decided mark on Middle-earth. He was an admirer of Macdonald’s fairy-stories (although later in life he came to regard them as rather too preachy). When his children were young, he used to read The Princess and the Goblin to them in the evenings, before they went to bed.

In a 1938 letter to the observer newspaper Tolkien stated that some ideas in The Hobbit ‘derived from (previously digested) epic, mythology, and fairy-story—not, however, Victorian in authorship, as a rule to which George Macdonald is the chief exception’.

‘Tolkien knew well Macdonald’s children’s books The Princess and the Goblin and The Princess and Curdie, both of which influenced Tolkien’s depiction of goblins in The Hobbit,’ writes Douglas A. Anderson in “Tales before Tolkien: The Roots of Modern Fantasy”.

Tolkien wrote in his essay “On Fairy-Stories”, that fairy tales might ‘be made a vehicle of mystery. This at least is what George Macdonald attempted,’ he expanded, ‘achieving stories of great power and beauty when he succeeded, as in “The Golden Key” (which he called a fairy tale); and even when he partly failed, as in Lilith (which he called a romance.)'

Numerous illustrators have contributed to George MacDonald’s work over the years. The work of three of them is included in this edition: Charles Folkard, Maria Kirk and James E. Allen. The images they created were all published during the lifetime of Professor Tolkien, so he almost certainly saw them. The colour plates are glorious, and although the prohibitively high cost of coloured printing-inks means that they appear in black-and-white in the print edition, you can see the full-colour versions in Leaves of Gold Press’s ebook edition.