The magical blending of times and spells in [Earthfasts] is made more effective by Mayne's matter-of-fact attitude. His tight, intricate plotting, skillful prose, and distinctive, individual characters, especially the drummer boy and gentle, passive Keith, combine with the immense profundity of his invention to make this one of the best of all fantasies, a classic of speculative literature. (p. 240)

Diana Waggoner, in her The Hills of Faraway: A Guide to Fantasy (abridged by permission of Atheneum Publishers; copyright © 1978 by Diana Waggoner), Atheneum, 1978.