Horus as bright as the sun was explained by a tale, known as "The Contendings of Horus and Seth". In this tale, it was said that Set, the patron of Upper Egypt, and Horus, the patron of Lower Egypt, had battled for Egypt brutally, with neither side victorious, until eventually the gods sided with Horus. As Horus was the ultimate victor he became known as "ḥr.w wr" "Horus the Great", but more usually translated "Horus the Elder". In the struggle, Set had lost a testicle, and Horus's eye was gouged out. Horus represented the eclipsing binary Algol in the Calendar of
The Horus Heresy (novels) series became a sales success in its category. "Horus Rising" by Dan Abnett, the opening title, set the pace shortly after its release, topping "Locus" magazine's "Locus Bestsellers: Gaming-Related" list of August 2006; practically every title in the series had achieved the same or similar performance on this chart. "Horus Rising"s January 2011 CD audiobook release also appeared in ranked sales lists: the (abridged) edition was number 15 in a related chart published by "The Bookseller", covering 2011 UK sales up to September. "Legion" by Abnett, and "Battle for the Abyss" by Ben Counter, were listed in Nielsen BookScan's list