One of the most important aspects of Tela Magica, as well as perhaps the most difficult, is the transition from the modern world to a mythic setting. This transition requires that we forget many of the concepts which form the bedrock of our society. Such values as equality, peace and the separation between Church and state are simply not part of the medieval mindset.
The mythic mindset is what the creators of Ars Magica (tm) call the medieval paradigm. Its premise is this: the world is the way medieval folks perceived it; their fears, dreams, beliefs and legends are manifest in reality. This means that the medieval stories and myths that we know can be true. Indeed, the setting of Mythic Europe is one in which legends come true - not necessarily all of them, but enough to make it a different reality from out own.
Poverty in the Middle Ages is believed to be inevitable. It is in one sense good in that it gives the wealthy the opportunity to practice the charity to assure themselves a high rank in paradise. Poverty is not an evil, but an essential part of life. At least to the nobility and the clergy that supports them.
Power is in the hands of those who feel no qualms in using it, not because they are heartless, but because their morals simply do not include some of our most heart-felt ideals. Killing an enemy's peasants and burning their fields, causing them to starve over the winter, is not much to speak of. Yet the nobility has its own code of conduct, and though it is as often breached as our own, it is the standard under which they proudly stand.
Crass and crude jokes told by both sexes are common until the Renaissance. For the men to go to another room to tell lewd jokes is a thing of our recent history, not of the Middle Ages. This is a lively age, with somewhat different social taboos and restrictions on the individual than what our society has.
People attribute much that occurs in their lives to the supernatural. Even a common cold is thought by most to be a minor possession by a demon.
Concepts such as time and law are not abstracts, but are concrete, tangible, material categories, just as tools and animals are, and are created by God in the same way. Concepts were treated in the same manner as "real" objects. Time is spent in the same way as money, and is squandered in a similar fashion.