The system of the eight circles of magic was developed by the mages of Britannia some time before Ultima V, in order to bring order into the list of magic spells, which up to then had been pretty chaotic and without much of a system.
They decided after long research of the workings of magic on a system where the spells were divided into eight circles of ascending difficulty. The more experienced the mage is, the higher the circle he or she can access. This is also reflected in in the mana cost, with is always equal to the number of the circle the spell is located in.
The system was not chosen by chance. These eight circles correspond with the ethereal waves, which are made up of eight rings or circles of ascending power. Each circle is one of eight swirling vortices, all spinning one within another and expanding out through the universe in the Ethereal Void. Unlike what a non-mage might think, the higher cicles are the inner ones, which are smaller and therefore more difficult to reach. Only master mages can hope to manage and access the 8th circle, which is an exclusive level, as hinted at by Xiao in Ultima VI.
Outside of this system stand the linear spells, which are part of no ring and therefore can be accessed without any mana cost at all, needing only a certain amount of intelligence to be used.
Note however, that the system of eight circles is restricted to Britannia.
On the Serpent Isle with its different connection to the universe, magic actually has nine circles of magic, but no linear spells. It is unknown why exactly this is the case, as the chaotic nature of the ether is a mystery still in the process of being discovered.
In gameplay mechanics:
- The level of the caster determines which is the highest accessable level. For example: level 4 = maximum circle is the 4th.
- The mana cost is equal to the level, i.e. circle 4 spell = cost of 4 mana points.
In the Ultima Underworld games, the spells are still divided into eight circles, but do not correspond with the levels, of which there are 15.
In Ultima VII Part Two, the system is expended to 9 circles by just making it more challenging to reach the ninth level.
|“|| Spells diverge greatly in terms of difficulty, and, correspondingly, in terms of danger to the caster. After years of observation and experimentation, scholars in magic have classified spells into eight circles of difficulty. Thus, mages who can command only the simplest spells are considered to be of the first circle, and so on.|
|“|| Mages with little training and experience are limited in the spells they can cast. As a spellcaster grows in stature, penetrating the mysteries of the highest circles of magic, he gains the ability to cast more powerful spells. Great power is not without cost, however. When he casts a spell, the mage experiences a drain in magical power equal to the level circle of that spell. Thus, a simple first level spell drains one point while a fifth level spell, more difficult to cast, drains five. The caster's magical power returns within a few hours.|
|“|| There are eight circles of magical spells, each successive circle representing a more powerful level of magical energy. The ethereal waves are made up of eight rings or circles which correspond to the levels of the spells. Each circle is one of eight swirling vortices, all spinning one within another and expanding out through the universe. The more powerful the spell a mage casts, the deeper into the inner circles of the ether must the concentrated psychic energy of the mage penetrate. Required for the mage are many, many hours of meditation, the strength of concentration, and the will to reach into one of the higher circles with his psychic energy. Every mage is fully aware that a backlash would upset our physical world, possibly harming the mage and those around him.|
|“|| The nine circles of magic are as profound and complex a study as any other in the realm. Each circle represents a ring of waves within the Void known as the ether, the envelope of energy that enables all spellcasting. The spells found on the outermost ring are learned first, and skilled mages will have most or all in their spell books. However, as a mage strives for each successive circle, the spells become more difficult to learn and master. Only Wizards of the higher circles are able to grasp the essence of the innermost spells. Here, listed by circle, are descriptions of all known spells, including their required reagents and words of power.|
|“|| The properties of the Element required for a spell place it in one of the Circles of Magic according to an exact formula. While the definition and nature of the properties are unnecessary for this Practicum, let it be said that the outer Circles of Magic require more control and experience to master.|