Magic: It's Alive!

Magic. It's one of the key features of any fantasy setting. It provides power and mystery that science fiction doesn't. In this setting, magic is not just another type of technology. It's a power with a life of it's own. Heat goes where it's cool. Things fall down. Magic ... Magic does it's own thing, it's 'squishy'. This means every time a caster draws in magic, they have to mold and shape it a little differently than the last time. And for each caster that same spell may need to be manipulated in a very different way. Each spell is it's own little surprise, waiting to go wrong.

This is why Continual Light isn't cast on every street corner, and people still wander with diseases. Learning magic is hard and few can do it reliably. Teaching magic, divine and arcane alike, has sometimes been compared to a deaf person with no hands trying to teach a blind person how to play the violin. Only harder.

That said, some very powerful casters have been able to create some very specific spells that can be taught without a great deal of difficulty. Like a master carver creating a woodcut for a lesser craftsman to stamp. These lesser caster are often employed to maintain complex magical works. It is said that the huge float ships that cross the Expanse are crewed by such casters.