Star Maker is a cornerstone work of science fiction. Stapledon undertakes the immense task of describing the entire history of life in the universe. It dwarfs in scale even his 1930 book Last and First Men, which is a history of the human species over two billion years. It tackles philosophical themes such as the essence of life, of birth, decay and death, and the relationship between creation and creator, and it succeeds in evoking a sense of the sheer scale and complexity of the cosmos. The narrator starts with a concern at the clash of ideas on Earth and finds analogies to both communism and fascism among the aliens he visits.
A pervading theme is that of progressive unity within and between different civilizations. Some of the elements and themes briefly discussed prefigure later fiction concerning genetic engineering and alien life forms. It has long been considered to be one of the finest works of science fiction ever written.
Stapledon imagines alien biologies, minds and civilizations radically different from human ones. But unlike Stanisław Lem's Solaris, all these are supposed to be fundamentally similar in the long run, since all are governed by the same Darwinian and Marxist laws of development. These views, rooted in the late 19th and early 20th century, may appear dated to some modern readers. The eclectic mix of popular science, socialism and religious mysticism is Stapledon's own.
Some of Stapledon's ideas for alien minds, such as collective intelligence, seem far ahead of their time, anticipating recent ideas about swarm intelligence and the general fascination with Network. He also mentions the idea of virtual reality in the first alien world visited, in the form of an apparatus that directly affects sense centers in the brain. The idea of entire worlds as spacecraft is used several times.
The novel is one of the most highly acclaimed in science fiction, but critics of the novel see it as full of interesting ideas but its writing as dull, dry, characterless, difficult, and even scientifically implausible at points. However, its admirers at the time of first publication saw it as one of the most brilliant, inventive, and daring science fiction books. Among its more famous admirers were H.G. Wells, Virginia Woolf, C. S. Lewis, Jorge Luis Borges and Doris Lessing. Borges wrote a prologue for a 1965 edition and called it “a prodigious novel”. Lessing wrote an afterword for a UK edition. Among SF writers, Arthur C. Clarke has been strongly influenced by Stapledon.
The book begins with a single human narrator from England who is, via unexplained means, transported out of his body and finds himself able to explore space and other planets. After exploring another planet (the "Other Earth") in some detail, his mind merges with that of one of its inhabitants, and as they travel together, they are joined by still more minds or group-minds. This snowballing process is paralleled by the expansion of the book's scale, describing more and more planets in less and less detail.
The travellers encounter many ideas that are interesting from both science-fictional and philosophical points of view. These include the first known instance of what is now called the Dyson sphere, reference to a scenario closely predicting the later zoo hypothesis or Star Trek's Prime Directive , many imaginative descriptions of species, civilizations and methods of warfare, and the idea that the stars and even the pre-galactic nebulae are intelligent beings, operating on vast time scales. A key idea is the formation of collective minds from many telepathically linked individuals, on the level of planets, galaxies, and eventually the cosmos itself.
The climax of the book is the "supreme moment of the cosmos", when the cosmical mind (which includes the narrator) attains momentary contact with the "Star Maker" of the title. The Star Maker is the creator of the universe, but stands in the same relation to it as an artist to his work, and calmly assesses its quality without any feeling for the suffering of its inhabitants. (This cynical point of view vis à vis God was the brain-child of the nineteenth century, not Stapledon's invention.) This element makes the novel one of Stapledon's efforts to write "an essay in myth making".