I have an idea for a specific fantasy-world and setting (for a pen&paper RPG), but I would like some thoughts of others on it. In particular, how such a world would lead to the formation of different kinds of societies and political/economical systems. What would they look like? How would they have evolved over time?
The basic setting
In this world magic is abundant and the human-like inhabitants (call them humans In from now on) of the world are the only creatures capable of casting/utilizing magic and, naturally, are dominating the world as a species.
The magic is a form of energy which a human possesses. It can be willingly 'used-up' by casting magic of all sorts, but a certain amount of magic energy is simply 'used up' by living, nurturing the body. (This can replace eating/drinking but does not have to.) If a human has used up all his energy, it means death. (If there is death before that, the remaining energy is released chaotically in a burst of light. However, usually a human would use all his magic to protect/heal as long as possible...)
Where does the magic come from?
Small amounts of magic can be 'harvested' from the world's sunlight similar to photosynthesis in plants. This process on average yields slightly more energy than a human would need on a daily basis, so that humans 'low on magic' (and hence near death) would usually become catatonic and 'stand around' (in the sunlight) until their magic is restored to certain minimum level. Over time, 'excess' energy accumulates which gives the ability to cast magic.
Every human is also born with a certain amount of magic - taken from the parents (both) at time of creation. The amount of transferred energy is somewhat related to the intensity of the action. However, transfer - and hence creation of new life - can only happen if both partners willingly participate.
This is now the crucial bit. In ancient 'pre-historic' times during evolution - when humans developed their magic abilities - they at one point learnt how to 'transfer' that energy between themselves. Similar to the evolutionary developed transfer during reproduction, this transfer can only happen if both participants willingly cooperate. One can neither steal nor force-feed magical energy.
This magic transfer enabled the 'social animal' human to be cooperative and steadily become the dominant species on the planet. Already early in history, 'magic transfer' started to play a similar role like money in our world. Just that it literally is a transfer of power (and life).
Giving this as a pre-text, I wonder what sorts of societies would have grown over time and how their inner workings would be. What would 'poor' and 'rich' mean? How 'balanced' would an economy be? Note that magic can not be stolen and people would generally not kill themselves by becoming unreasonably poor. On the other hand, these humans would not necessarily be 'good' in their nature - they are as fallible to darker emotions and motivations as we are. So greed, power-hunger, envy and the lot will be part of this world, as well as social mechanism (working or not) to keep those in check.
In my RGP setting I'm aiming at a world which has historically evolved to the equivalent of the medieval times - so not a fully modern society (yet) - but I'm highly interested in how the 'history' of such a world would have developed from the beginning to this state, and how this 'medieval' time therefore is structured.