premise: The Colour of Magic is a 1983 comic fantasy novel by Terry Pratchett, and is the first book of the "Discworld" series. The first printing of the British edition consisted of 506 copies. Pratchett has described it as "an attempt to do for the classical fantasy universe what "Blazing Saddles" did for Westerns."
hypothesis: "Discworld" begins with the novel, "Discworld".
reason: "The Colour of Magic" is the firsts novel in the Discworld series as mentioned in the text.