This will be super weird, but since it's a request for an illustration of synesthesia on a thread about a mystifying codex, here goes:

The way I write short stories is to "tell it like you remember it," which triggers a kind of stochastic stream of consciousness on the theme, and it maintains its internal logic because one event flows from the next, within a boundary or limit, not unlike a random walk. This makes them seem more real because the honesty isn't in the events as described, but the feeling and plausible logic that generates them. There's a state that with some practice you can kind of summon, and it's a bit musical.

The same goes for music that has shapes, the best way I can describe that is imagine the notes as you hear them are the chaotic edge of an advancing wave but you can get above it and see upstream of them. You're sort of exploring adjacent leaf nodes in a tree made of scales. Key changes and other more complex techniques transfer to branches, etc. For me the colouring is produced by harmonic content of the instrument, where a pure sine wave above a certain frequency would be blue/white and harmonics and distorions and reds begin appear as you add them. The colours are more of an artifact of modulation than frequency.

This made me really interested in fractals because the self similarity resembles that upstream generation of the notes, and I'm playing with the idea now to see if I can validate it. Synthesis removes the barrier of refined playing ability from being able to reason about the shape of music, and treating it as very real shapes but ones you can't see. This is the link to maths, as like music, maths is also the specification of shapes you can't see.

We can say "patterns," but I find that word is too loaded with other meanings and doesn't express the edges and boundaries of the abstractions I (and others) think about, so we can cease to understand "patterns" that are more sophisticated than those that are just objects laid out in 3d space, whereas a shape automatically implies a bounded concept, with "sides" that you know are still a part of it but not visible, and isomorphisms you can relate to it. That intuition allows you to navigate the sense or idea. The shape can also morph or move, which adds additional dimensions to the variables you're thinking about it in terms of.

We're well into the territory of a bit loopy, but if you've read this and get it, I'd wonder if in a few weeks we might find synesthesia is transmissable via writing?

Have you ever seen the Veritasium video on where fractals actually come from in 3D? If not, and since you already thought fractals were fascinating, hold on to your hat.

https://youtu.be/ovJcsL7vyrk