An evolutionary epic disguised as a space opera. Generations pass between chapters, and the book asks you to care about a civilization the way you would normally care about a single character. The slowness is the point.
Evolution is the real subject. The book sits with how much of what we treat as moral instinct turns out to be older than morality. The dislike of what is different from us is biological before it is anything else. The other intelligence in the book evolves along a separate track and arrives at its own shape for conflict, its own form of communication, and a way of passing knowledge across generations that is closer to inheritance than to teaching.
A thought experiment about time, scale, and what minds become when they have nothing in common with each other, run at a length only fiction can sustain.