Терри Пратчетт - The Colour of Magic

Since the Hub is never closely warmed by the weak sun the lands there are locked in permafrost. The Rim, on the other hand, is a region of sunny islands and balmy days. There are, of course, eight days in a disc week and eight colours in its light spectrum. Eight is a number of some considerable occult significance on the disc and must never, ever, be spoken by a wizard.

Precisely why all the above should be so is not clear, but goes some way to explain why, on the disc, the Gods are not so much worshipped as blamed.

Although in Trob the last word in fact became “a thing which may happen but once in the usable lifetime of a canoe hollowed diligently by axe and fire from the tallest diamondwood tree that grows in the noted diamondwood forests on the lower Slopes of Mount Awayawa, home of the firegods or so it is said.”

Wizards, even failed wizards, have in addition to rods and cones in their eyeballs the tiny octagons that enable them to see into the far octarine, the basic colour of which all other colours are merely pale shadows impinging on normal four-dimensional space. It is said to be a sort of fluorescent greenish-yellow purple

Being Unseen University failed.

Eight was also the Number of Bel-Shamharoth, which was why a sensible wizard would never mention the number if he could avoid it. Or you’ll be eight alive, apprentices were jocularly warned. Bel-Shamharoth was especially attracted to dabblers in magic who, by being as it were beachcombers on the shores of the unnatural were already half-enmeshed in his nets. Rincewind’s room number in his hall of residence had been 7a. He hadn’t been surprised

During his life they had appeared to others to be eight-faceted and eerily insectile.

Owing to the density of the magical field surrounding the disc, light itself moved at sub-sonic speeds; this interesting property was well utilized by the Sorca people of the Great Nef, for example, who over the centuries had constructed intricate and delicate dams, and valleys walled with polished silica, to catch the slow sunlight and sort of store it. The Scintillating reservoirs of the Nef, overflowing after several weeks of uninterrupted sunlight, were a truly magnificent sight from the air and it is therefore unfortunate that Twoflower and Rincewind did not happen to glance in that direction.

Water on the disc has an uncommon fourth state, caused by intense magic combined with the strange desiccating effects of octarine light it dehydrates, leaving a silvery mildue like free-flowing sand through which a well-designed hull can glide with ease. The Dehydrated Ocean is a strange place, but not so strange as its fish.

Plants on the disc, while including the categories known commonly as annuals, which were sown this year to come up later this year, rieanuals, sown this year to grow next year, and perennials, sown this year to grow until further notice, also included a few rare re-annuals which, because of an unusual four-dimensional twist in their genes, could be planted this year to come up last year. The Vul nut vine was particularly exceptional in that it could flourish as many as eight years prior to its seed actually being sown. Vul nut wine was reputed to give certain drinkers an insight into the future which was, from the nut’s point of view, the past. Strange but true.