This series of posts starts here.
This is so important and so applicable to play that I am going to have to break the chapter down into relevant chunks. Also, although I hate the distinction theoretically, practically speaking it is sometimes useful to distinction between "fluff" and "crunch." Most of what Lewis is doing here in the DI is more applicable to campaign "fluff." But I believe some of it may affect mechanical decisions or even provide clever accounts of mechanics that already exist in the game. This is true, I believe, especially with regards to "influence" and D&D "Vancian" magic.
A. The Parts of the Universe
"Thus while every falling body for us illustrates the 'law' of gravitation, for them it illustrated the 'kindly inclining' of terrestrial bodies to their 'kindly stede' the Earth, the centre of the Mundus." p. 92. Lewis does a lot of work to help us to get the feel of the difference between a natural philosophy based upon a theory of influence as opposed to our modern "empirical" natural philosophy based upon law. And he gives a really great "touche" (very Lewis-like) when he shows how our modern talk of "law" is just as metaphorical about inanimate objects as "influence," if not more so. But the medieval human being lived and moved in a world absolutely brimming with overlapping confluences of influence. All the stars and their signs, the seven planets including the various phases of the moon, the four elements, all overlapped and flowed in and out of each other, creating new situations every moment, day, season, etc.
This is so great because it is just as cool if not cooler than 1e's crazy cosmology but it actually corresponds to what we used to believe! So, a cosmography for a campaign world:
Earth at the center, water on top, air on top of that, fire as an invisible barrier right at the orbit of the moon. Really, fire distinguishes the super from the sub lunar realms. Very cool. These would be the "locations" from which the elementals are called forth. And above the moon all is bathed in the quintessence, aether. Perhaps we would need to invent another elemental that only the highest level MUs could call forth: the Aether Elemental! (Please, someone imagine this and stat it out for me!)
The four contraries: hot/cold / / dry/moist: combine together to make the four sub-lunar elements: fire = hot + dry; air = hot + moist; water = cold + moist; earth = cold + dry. Again, this would be great for campaign flavor, but as someone dedicated to rules-light play, I cannot see this affecting game mechanics for players in any way. Perhaps for the ref for a table for discerning MU elements, etc.? Thoughts?
Now we actually have something for the spell "Contact Higher Planes" to correspond to!
Terrestrial or perhaps Ethereal, or perhaps Elemental (guiding spirit: Fortuna (see later chapters))
Then he launches into a great exposition of the different "feel" of the cosmos b/w us and the medievals. "The Medieval Model is vertiginous." (98). So "space," for us, is this vast endless sea of vacuum. The "cosmos" for them was full of light and music but, imaginatively speaking, equally vast. But with a clear "up / down" so that we get vertigo when we look up at night! I love that.
More to come when I comment on the next section, but I can see all this really helping to make sense of D&D's magic "system." The "influences" could be part of an account of what a MU "knows." Their knowledge is more intuitive than theoretical (sage's knowledge is the reverse, more theoretical than intuitive -- thus they do not (or rarely) cast spells and never adventure!). They "feel" the influences of planets, spheres and lay-lines. Thus they know how to move their hands and which words of power to shout in order to "cast" the spell they are "holding" in their "memory" into the terrestrial plane at the moment they need it. They may not even be able to explain what they just did. But due to powerful initiations into mysteries and to their own on-going experience of the use of such intuition they more and more just "get the feel" for casting a spell. Spell casting becomes a kind of intuitive channeling and shaping of comic influences all around. No sorcery. Very natural. They know how to run the martial plane through a "sluice" and gain power and pressure on that influence like a miner knows how to use a pick and a carpenter knows how to sink a nail.