In a succession of distinguished books, Zilpha Keatley Snyder has been exploring the nature of magic, not only for the benefit of children, one feels, but to satisfy herself—which is, of course, how all good books are written. Invariably at the center of her magic is an oddball—a highly individual, nonconforming, compelling character, so inventive … as to suggest that magic lies within the power of imagination itself. (p. 8)
With each book the pattern of Mrs. Snyder's magic becomes clearer, more closely entwined with reality. In one sense, her characters are themselves the magicians. Unlike Alice, who emerges from her rabbit hole ready to take up childhood just where she left off, they are never quite the same after their adventures. And indeed, one asks, how can magic not leave a mark?
"The Witches of Worm" is one of Mrs. Snyder's most haunting stories and one of her deepest probes. For the first time she speaks from the point of view of the magic maker Jessica, whose anger and loneliness are the driving force behind the plot as they are so often in this author's work….
Witches, Mrs. Snyder contends, are those who have learned the trick of making people believe that nothing they do is their own fault. Here is the essence of the theme that recurs in her books, always in fresh form but never so well articulated: magic is, on the one hand, the projection of forces that lie in the human psyche, and on the other hand, it is mystery.
Perhaps because she never underestimates the mystery, perhaps because she walks the thin line between real and phantom worlds so knowingly, Mrs. Snyder's brand of fantasy is convincing on many levels. Certainly we are ready to believe that Jessica, having come to terms with the source of black magic, will have no trouble practicing white magic with Brandon—who, happily, is restored to her in the final pages. Indeed, we would like to be around it. (p. 10)
Jean Fritz, "For Young Readers: 'The Witches of Worm'," in The New York Times Book Review (© by The New York Times Company; reprinted by permission), December 10, 1972, pp. 8, 10.