In my world, magic has been granted to mortals by their gods.
As a result, the Church heavily regulates it, and the only legal spellcasters are clerics and clergymen. Magic use is heavily regulated by a continent-wide neutral organisation of high clerics, bishops and cardinals (think of it of something like a crossover between the OSHA - for the safety and regulation side- and some kind of Inquisition -to take care of the moral side and prevent blasphemy): you need to pass exams, acquire a certification and become an "authenticated" magic user before you can cast a single spell.
Usually, casting a spell requires the user to call upon the forces of the Divine (by drawing from the "mana" pool generated by the gods), but a cleric and a doctor found that one can cast a spell by either using the God's mana pool, or using the mana generated by every human, animal, plant or insect. They compiled all their information in a white paper and broadcast it to the continent, thus sowing the seed for a revolution in the spellcasting domain. Think of it like Satoshi Nakamoto's White paper, in terms of cultural impact.
By using this method, you basically remove the safety guards that come by calling upon the forces of the Divine: casting spells become more dangerous, but anyone that practices enough can cast spell as well as a cleric, whilst not being a registered user and not using the might of the Gods.
- Being a Renaissance-level setting, printing presses are a common occurrence, and paper production is not an issue. The technology is advanced enough so the white paper can be printed on a A4/A5 format tops.
- Information can be transmitted almost instantly via magic, but needs a special magic item in order to display it to human eyes. Spellcasters can still feel/hear/sense in some way the message.
- This is between a medium and high magic setting, kinda like in Andrzej Sapkowski's The Witcher works or Blizzard Entertainment's Warcraft series.
Infrastructures, organisations and culture
- War has been around for a while. Rare are the periods of peace, thus hospitals and science academies are already built. Same goes for magic colleges, big and small.
- A lot of people from all social classes are dissatisfied with the current magic regulations. Protests and open letters have already tried to relax the regulations, but nothing changed. Underground spellcasters associations and unions are relatively common, acknowledged by the Church but barely tolerated.
- Basic education is quite common, and children often work with their parents part-time while going to school (or work and learn on alternating weeks). Hence, the literacy rate is rather high and homogenous for a Renaissance-level setting. Nobility will have access to more prestigious colleges, but basic knowledge and skills are learnt by a large part of the population.
- Great archives are present in every major city. Containing documents of all kinds, about two thirds of the non-confidential and non-governmental documents are available to the public.
Here is the problem: how can the doctor and the cleric that wrote the white paper broadcast it sneakily enough to not attract the attention of the Church, but at a wide enough scale to kickstart underground experiments (and finally, allow commoners to cast (often non-combat) simple spells)?