Will is shifting out of childhood. The world reveals itself differently to him. Archetypal energies move back and forth between myth and modern times; the Rider, the Walker appear as the troubling friend of his father, the tramp mobbed by crows. The power of the light emerges out of the neighbouring farmer or the lady of the manor. Shapes shift, reality wobbles.
Susan Cooper tackles specialness. Will has to come to terms with his individuality, his difference from the rest of his family, whom he loves but can longer wholly confide in. He finds he has powers and a unique purpose, but still must learn the nature of both. Above all he learns, simply, but very importantly, to stand his ground, to hold to his truth even when it feels it may be his alone.
Here is a writer with a feel for the land; her story is precisely located besides the Thames, over the water from Windsor Castle. Her myths are the accumulated myths of Britain. Her moral light and dark has an urgency, perhaps made more powerful by an uncertainty about what either does or is.
Unlike E. Nesbit (whose Phoenix and the Carpet she tips her hat to) or C.S. Lewis who use an amulet or a wardrobe to move into another world, she allows this blending of realities and dimensions to be more internal; there’s a greater recognition of Will as an active agent of his movement between worlds.
Perhaps the writer who most clearly offered her such a way is John Masefield of The Midnight Folk and The Box of Delights. There is a love of language, a willingness to patchwork together whatever serves and a deep love for the country itself, not only as physical landscape, but as of a progenitor of spiritual, moral or legendary truths.