This work first appeared, in serial form, in 1969, a time of changes for Robert Silverberg himself and for the field of science fiction. After years as an unusually prolific hack, Silverberg stopped writing science fiction in the early 1960’s. He returned a few years later to write more serious science fiction, with more attention to the literary virtues of characterization and prose style and with a willingness to look to the so-called “mainstream” for examples. Along with such books as Tower of Glass (1970), The Book of Skulls (1971), and Dying Inside (1972), Downward to the Earth represented this sort of literary ambition. The field as a whole was undergoing similar changes, sometimes referred to as the “New Wave.”
The book contains a number of references to Joseph Conrad’s well-known treatment of the theme of clash between European and “primitive” cultures, Heart of Darkness (1902), most notably the name of Kurtz. It employs one of Silverberg’s most frequent themes, redemption and rebirth, as well as treating an issue that was much in the news at that time, colonization and the return to native rule. Some saw the natives as less than human; others saw them as having an enviable connectedness to the land and to other life. Silverberg extended this in science-fictional manner by making the nildoror nonhuman in appearance but intelligent in their own way and even telepathic.
This did not represent a simple concession to current political fashion on Silverberg’s part. Indeed, as far back as Invaders from Earth (1958) and Collision Course (1961), he had been suggesting that the alien races Earth might meet could be wiser or more clever than humanity. This approach put him on a collision course with dominant forces in the field of science fiction, most notably John W. Campbell, Jr. Since then, the idea of alien cultures as different, rather than inferior, has shown up in many books, including Ursula K. Le Guin’s The Word for World Is Forest (1976) and Barry B. Longyear’s Manifest Destiny (1980).
With its lavish descriptions of alien landscapes, its rich development of characters both alien and human, and its striking presentations of altered states of consciousness, Downward to the Earth is generally considered one of Silverberg’s best novels, at least by those who do not prefer the simple adventures of his early work.