My setting features what I call "psionics", essentially magic that I want to limit in scope and feeling of mysticism. Until a certain point in the story, psionics is relatively rare and varied, and psions are often struck with mental afflictions and erratic behaviour. Some powers they might have:
- Manipulating organic matter like wood, flesh and fungus
- Healing and manipulating blood or bodily tissue
- Perceiving and affecting another living thing's senses and emotions
- Archiving, psions being able to manipulate special devices to quickly and effectively journal their surroundings, such as proto-cameras and writing in several places at a time
- Misshapen people, perhaps half-fused with plants, animal traits or fungi
At some point, the source of psion madness is found to be an eldritch-y abomination / ancient disruptor that is destroyed, with the main character partially merging with it. Weaker creatures of the sort are then discovered and harnessed into the "weave", the ultimate form of psionics, where a black, inky mass shaped into tendrils, weaponry, inks and other applications becomes mainstream. This creates several other forms of magic:
- The "big" form of it that starts dominating society, where people use small quantities of it to replace lost limbs, build more quickly and express themselves
- Weavelings, semi-autonomous golems
Aspects interacting with psionics include mental illness (swerving users to visualise and either control or unleash their neuroticism), drugs, and being in the company of others.
My problem is, this seems pretty all over the place, and as the story progresses, I want at least one civilisation to essentially turn the rare, mysterious force into what's essentially another aspect of the human body (like how most people have a voice, some have extraordinary voices through training, some have unique ones, etc.), and scientific discovery that changes warfare and philosophy.
I want a "unifying theory" or a top-level description of how and why it works that way, that can prevent it from blowing up into a lot of magical clutter, or unpredictable, hard to account for variety. "The mind can alter reality" isn't good enough, as I need it to be obvious that it can't, for example, shoot lightning or make people fly or grant invisibility.
And on the writing side of things, how can I use this theory without over-explaining things, a la "midichlorians"?