The creative complexity of Clarke’s novel has made it a classic of modern science fiction. The work is difficult to categorize or synthesize. On one level, it operates as a reasonably believable extrapolation from modern scientific and technological progress into a material utopia. The novel has its dystopian psychological dimension as well. Childhood’s End also reflects the aspect of Clarke’s writing most fully realized in 2001: A Space Odyssey (1968), his creation of brilliantly evocative, colorful, fantastic descriptions of nonexistent other worlds as an exercise in human imaginative expression. The description of the metamorphosis of the mountain on NGS 549672 in Childhood’s End is an excellent example. Closely allied with this fantastic physical description is the imaginative leap made by Clarke in his depiction of the fantasy transformation of human children into psychic superpowers and spiritual essences.

Also intimately connected to this imaginatively mystical element in Clarke’s writing is his recurring theme of religion—particularly Christianity—as an imperfect embodiment of powerful but misunderstood psychic and spiritual forces. For example, in the 1956 Hugo Award-winning story “The Star,” Clarke ironically presents the star of Bethlehem as the supernova stage of another planet’s sun. Billions of people die on that planet as the supernova guides the shepherds to the place of birth of one child on Earth. The same reversal of Christian belief, or enlargement of the context surrounding it, is obvious in Childhood’s End, with the Overlords as an ironically benevolent reversal of the human image of Satan.

Also fundamental to Childhood’s End is Clarke’s recurring theme of the existence of, and inevitable human contact with, other life-forms in the universe. With an intensity akin to religious conversion, Clarke presents this theme in his famous 1951 story “The Sentinel,” the progenitor of 2001: A Space Odyssey. On a moon expedition, the narrator of “The Sentinel” finds a crystal pyramid left by an alien species and accepts the fact of that species’ existence; similarly, the Overlords’ arrival in Childhood’s End is represented as an inevitable progression in human encounters with the life-forms “out there.”

In its complexity and multifacetedness, Childhood’s End represents the great artistic power of Clarke in all three of his writing styles, which, according to James Gunn in The Road to Science Fiction: From Heinlein to Here (1979), are extrapolative, ingenious, and mystical. What the novel lacks in formal unity and harmony it more than compensates for in pure energy, originality, and profundity.