Edition: Wm. B. Eerdmans
Today MacDonald is perhaps best known for his childrens books, particularly The Princess and the Goblin, but (like Hans Christian Andersen) he also wrote for adults. He was one of the nineteenth century precursors of the modern fantasy genre, along with William Morris (whose work Phantastes closely resembles) and collectors and writers of fairy stories such as Hans Christian Andersen, the Brothers Grimm, and the Celtic revivalists. Through his influence on Tolkien and C.S. Lewis, MacDonald has come to have an effect on twentieth century literature rather greater than his innate literary merit deserves.
Part of what doesn't quite come off about Phantastes is that it is almost completely devoid of plot. The narrator stumbles into Fairy Land, where, after several adventures in a wood he gains a shadow (beyond his natural one); the remainder of the book is spent in an attempt to perform good and valiant deeds to remove it. It is akin to the individual quest which is part and parcel of the fantasy genre (deriving from medieval epics detailing the adventures of knights), mainly because Tolkien used it in The Lord of the Rings. But the journey is not really sufficiently purposeful here to be called a quest; the reader gets the distinct impression that the narrator is wandering aimlessly from one adventure to another.
The positive side to this lack of plot is that it gives Phantastes a dreamlike, poetic quality (though the actual poetry that appears in the book is best skipped, as in so many later fantasy novels). This is particularly true of the best episode in the novel, the time spent by the narrator in the castle of the Fairy Queen, trying to catch a glimpse of the courtiers invisible to normal human eyes.
A major aspect of Phantastes, and one strong influence on Tolkien and particularly Lewis, is the allegory. Many of the episodes have an allusive, symbolic quality, typical of medieval allegories such as Piers Plowman, though the symbols used by MacDonald here are sufficiently personal to make interpretation difficult if not impossible. From clues in the text, and given that MacDonald was an ordained (if somewhat eccentric) clergyman, it is reasonable to guess that part of the thems of the novel is to allegorise the Christian life. Fairy Land represents the spiritual world in which the Bible insists a Christian lives, with both good and evil spirits; the shadow is the soul's load of sin (as in The Pilgrim's Progress). Beyond this it is difficult to go, though there is an extremely clear picture of death and the resurrection towards the end of the book.