Anathem is the first and most conspicuous example. It is a play on the words anthem and anathema, which derive from Latin and Greek words. Orth, the classical language of Arbre, has a completely different vocabulary, and so the words for anthem, anathema, and anathem are altogether different, and yet linked by a similar pattern of associations. Rather than use the Orth word, which would be devoid of meaning and connotations to Earth readers, I have tried to devise an Earth word that serves as its rough equivalent while preserving some flavor of the Orth term. The same thing, mutatis mutandis, has been done in many other places in the book.

Names of some Arbran plant and animal species have been translated into rough Earth equivalents. So these characters may speak of carrots, potatoes, dogs, cats, etc. This doesn’t mean that Arbre has exactly the same species. Naturally, Arbre has its own plants and animals. The names of those species’ rough Earth equivalents have been swapped in here to obviate digressions in which, e.g., the phenotype of the Arbre-equivalent-of-a-carrot must be explained in detail.

A very sparse chronology of Arbre’s history follows. None of this will make very much sense until one has read some pages into the book, but after that it may be useful for reference.

— 3400 TO-3300: Approximate era of Cnous and his daughters Deat and Hylaea.

— 2850: Temple of Orithena founded by Adrakhones, the father of geometry.

— 2700: Diax drives out the Enthusiasts, founds theorics on axiomatic principles and gives it its name.

— 2621: Orithena destroyed by volcanic eruption. Beginning of Peregrin period. Many surviving theors gravitate toward city-state of Ethras.

— 2600 TO-2300: Golden Age of Ethras.