It is written by an author who is evidently a student of ecology. Stewart writes lengthy passages to describe how the local environment changes after being unfettered by man. We see marks of modernity subsumed gradually by nature, as grass and trees encroach roadways, block drainage systems, and create localised flooding. Furthermore, we see unanticipated changes to animal populations. All of this is presented in a credible way so that the novel becomes more compelling.
Despite the challenging new ecology, Ish succeeds in meeting a woman and attracting a small group of survivors into settling around him. He aims to hold onto the vestiges of modernity and has initial success. However, we see over a period of decades how difficult a task this is for the protagonist as disease, mortality, and human nature impose a simpler way of life in a post-apocalyptic world.
Most intriguingly, the novel explores explicitly the question of where any given change in a society comes from. Does progress come from within man, or from the environment? Stewart views these as two opposing sides of an equation which governs a greater balance. However, balance is either short-lived or never quite reached, because man and environment adjust to eachother imprecisely.
Overall, the book contains many interesting observations of modern man, primitive man, society, and nature, with philosophical passages that often reference the Old Testament (Ecclesiastes.) While doing this, the novel remains lucid, engrossing, and plainly written, which emphasises the achievement of the author.