Terry used the Discworld to explain many of his own Ideas. He also ported a fair amount of Ideas proposed by others in our world into his universe.
The list below contains the ones I felt compelled to pull out of the book series. It is in chronological order by book and within each book.
Each idea is presented here only once as found in the book in which Terry first discussed it. If something significant about the idea is added in a later book, I’ll add to the description given in the earlier book.
Since there are relatively few such Ideas (compared to Persons, Places, and Things), I don’t intend to do any more with this list than what you see here. If I change my mind later, this paragraph will change with it.
Ideas in The Colour of Magic
Big Bang Hypothesis vs Steady Gait Theory – Two competing Ideas about how the Great A’Tuin moves through space. Neither may be correct.
Law of Conservation of Reality – “The effort needed to achieve a goal should be the same regardless of the means used.”
The Eight Great Spells – Seven are still in The Octavo; one is in Rincewind’s brain. No one knows what they are or what they do. That’s probably a good thing.
Mage Wars – Early in the Disc’s existence, these cause the Gods to be banished to Dunmanifestin, man to be re-created in smaller form, and wild magic to be sucked out of the Disc. And something more of significance.
Time, Non-Existence of – From Greicha the First (deceased but ruling) of Wyrmberg: “Imagine every moment being at one and the same time a distant memory and a nasty surprise….”
Seminal Ideas in The Light Fantastic
Librarian, Creation of – “The room had been part of the library until the magic had drifted through, violently reassembling the possibility particles of everything in its path. … And several of the wizards later swore that the small sad orang outang sitting in the middle of it all looked very much like the head librarian.”
Rite of AshkEnte – Summoning Death either by an elaborate ceremony, if there’s time, or something quite basic, if there’s not.
Hogswatchnight – The last night of the year when the Hogfather does his thing.
Thaum – The basic unit of magical strength. Often prefaced with prefixes like kilo- and mega-.
Tourism – According to Twoflower, the Disc’s inaugural Tourist: “I often don’t know where my Luggage is, that’s what being a tourist is all about.”
Multiple Universes – Often called (in other works) the Multiverse. According to the shopkeeper of one of those shops when asked what he would do next: “Oh, go to some other universe, there’s plenty around.”
Far Side of Darkness – Terry often goes through an idea to its other side or far side. He does so here with Darkness to create The Light Fantastic.
New Ideas in Equal Rites
Borrowing – When a witch gets into the mind of an animal (or the occasional University) and sees the Discworld through it.
Headology – Why a witch’s appearance and manners are more than they seem, according to Granny Weatherwax.
Metterfors – Granny’s term for metaphors. These aren’t particular to Equal Rites, but I decided to use them to create my main review of said novel. Thus I turned them into a 7A-part series of articles as listed below.
- How to Write Like Terry Pratchett: Similes and Metaphors in Equal Rites
- Writing Like Terry, Metterfors, Part 2
- Terry’s Metterfors, Part 3
- Metaphors in Equal Rites, Part 4
- Equal Rites Metaphors, Part 5 – What’s Not to Like?
- More Metaphors in Equal Rites, Part 6
- Penultimate Studies in the Metaphors of Equal Rites, Part 7
- Metterfors in Equal Rites, Part 7A, the Last
Hogswatch Day – The first day of the year in Discworld. In the roundworld, it would be both Christmas Day and New Years Day.
New Ideas in Mort
Hogswatch Eve – Virtually the same as Hogswatch Night. The equivalent of Christmas Eve in the roundworld.
Schism of the Turnwise Ones – Something to do with pizza and a jihad that caused the death of 25,000. Probably best not to ask.
New Ideas In Sourcery
Eve of Small Gods – When a new Archchancellor of Unseen University is “elected”.
All-Wadi Imperturbability Championship – The current holder is normally one tough dude. Normally.
Year of the Hyena – In force during the course of Sourcery.
Soul Cake Thursday – Later found to occur on a Friday and on a Tuesday.
New Idea in Wyrd Sisters
Sumtin, Philosophical system of – According to the Fool, Zen is a sub-sect of this Turnwise Klatch system. Who’s to argue?
New Ideas in Pyramids
Year of the Engaging Sloth – During which the Thieves’ Guild declared a General Strike. The actual crime level doubled.
Smoking Mirror, Secret rituals of the – In which we learn of Nesh. Other rituals from Pyramids could be included here but are not.
Year of the Cycle of Cephnet – Imagined by Teppic while falling asleep. So it might not be real.
Century of the Cobra – During the time of Teppic.
Century of the Fruitbat – Not during the time of Teppic.
Troll’s Head – A tavern in Ankh-Morpork whose customers aspire to become the dregs of humanity.
New Ideas in Guards! Guards!
Grune – Seventh month of the Common Year. Between June and August. This being the time of change when the sun doth rise on the Right when facing the Hub.
Knurd – The state of not being drunk that goes beyond sobriety.
New Ideas in Eric
None. In fact, the only idea (by my definition, which is the only one that counts here) mentioned is the Rite of Ashkente.
New Ideas in Moving Pictures
Nothing to speak of here either, unless you count Holy Wood itself.
New Ideas in Reaper Man
Finally something new again. Actually, most are quite old as they are time-related.
Year of the Intimidating Porpoise – When old ‘Scratcher’ Hocksole Went Away.
Century of the Dragonfly – In which a ruler of Ankh-Morpork had tried to tell the wizards what to do.
Year of the Impromptu Stoat – Per the Farmer’s Almanac and Seed Catalogue, on June 15, 150 yrs. since, a Man killed by Freak shower of Goulash in Quirm.
Soul Cake Night – On which the young may go trickle-treating.
Year of the Significant Triangle – Year in which Windle Poons was born.
Century of the Three Lice – Century in which Windle Poons was born.
Year of the Notional Serpent – Year in which Windle Poons died.*
*This was within the Century of the Fruitbat.