Prior to the publication of "Last and First Men: A Story of the Near and Far Future" in 1930, Olaf Stapledon had already published a couple of short stories, poems, including a book of poetry, a non-fiction book "A Modern Theory of Ethics: A Study of the Relations of Ethics and Psychology", and numerous essays. However, this was his first book of fiction, and remains, if not his most famous work, than one of his two most famous works. While clearly Stapledon's fictional work falls into the category of science fiction, in many ways it is unique and while it is easy to find authors who were influenced by Stapledon, it is much more difficult to find an author who has significant influence on Stapledon's work.
The narrative of "Last and First Men" is driven by ideas, and not by characters, and in many ways this is true of all of his fictional work, though certainly novels like "Odd John" and "Sirius" have characters and take on the appearance of a standard novel. The novel has tremendous scope, the narrative being given from billions of years in the future by a member of the last race of men, i.e. the Last Men who are aware that they will destroyed and thus be the last of men. They story covers the cyclical nature of the history of the First Men, i.e. us, and the cyclical nature of many of the races of Men who follow. It also discusses the psychology and the philosophy of the races as well as some of the physical and physiological changes.
The journey into the far future moves faster and faster as it continues. A fair amount of time is spent on the First Men and our future both near and far. This speeds up as Stapledon takes us through the Second through Fifth Men and faster still until he reaches the Last Men. He covers many concepts such as genetic engineering, terraforming, alien invasion, biological warfare, and so on.
The cyclical nature of many of the things he discusses tends to make parts of the novel a bit repetitive, and so I believe that it detracts a bit from the overall effect of the novel. That being said, it is still an extraordinary novel and unlike anything else you will likely ever read, with the possible exception of Stapledon's "Star Maker" which has a similar scope as well as an unusual narrative, but also has a different feel. Stapledon did not finish with the idea of the Last Men with the publication of this novel, as he returned to the idea in his radio play "Far Future Calling" in 1931 where he amazingly puts the novel in dramatic form, but which sadly was never performed. He also returned to the idea for his second novel "Last Men in London" in 1932, which focuses on a look back at the 20th Century from the perspective of one of the Last Men.
This book was rated 3rd on the Arkham Survey in 1949 as one of the `Basic SF Titles'. It also was tied for 30th on the 1975 Locus All-Time poll for Novels; 43rd on the 1987 Locus All-Time pool of SF Novels, and tied for 43rd on the 1998 Locus All-Time Poll for Novels written prior to 1990.