The first few chapters of the novel dealing with the discovery of Erewhon are in fact based on Butler's own experiences in New Zealand where, as a young man, he worked as a sheep farmer for about four years (1860–64), and explored parts of the interior of the South Island.
The greater part of the book consists of a description of Erewhon. The nature of this nation is intended to be ambiguous. At first glance, Erewhon appears to be a Utopia, yet it soon becomes clear that this is far from the case. Yet for all the failings of Erewhon, it is also clearly not a dystopia. As a satirical utopia, Erewhon has sometimes been compared to Gulliver's Travels (1726), a classic novel by Jonathan Swift.
Erewhon satirises various aspects of Victorian society, including criminal punishment and religion. For example, according to Erewhonian law, offenders are treated as if they were ill, whereas ill people are looked upon as criminals.
There are three chapters of Erewhon that make up "The Book of the Machines." Butler developed them from a number of articles that he had contributed to The Press, published in Christchurch, New Zealand. Butler was the first to write about the possibility that machines might develop consciousness by Darwinian Selection.
[adapted from Wikipedia]