When spellcasters prep a spell, they are creating an entanglement between their souls and the quantized fields of ley energy which permeate the cosmos. (Or, more accurately, they shape their spiritual valence – the “surface” at which the soul’s energy interfaces with the rest of reality – to create specific desmata, or channels, which are entangled with the ley fields. Hence, channeling magic.)

This process is incredibly dangerous. If the entanglement goes wrong, a spellcaster can essentially “ground” themselves – becoming (very briefly) a living conduit through which unrestrained magical energy pours into the Material Plane. At best, this can burn out some or all of the caster’s magical potential, creating a scar on their soul. Usually such events simply kill the caster outright.

In practice, arcanists have learned very stable configurations of entanglement. Different bodies of arcane theory feature different stable patterns through which they progress, but, for example, wizards have perfected patterns for creating two entanglements with the first sphere of energy (1^st level spells), another for four entanglements with the first field of energy and two with the second field, and so forth.

Magical theory believes that the nature and shape of the ley fields are due to the configuration of the major planes. The “turning of the Great Wheel” or “branchings of the Great Tree” are really just metaphors for how arcanists believe energy flows through the multiverse. (This is also why you may hear some arcanists referring to the “first sphere” or “seventh sphere” of magic, while others refer to the level or branching or so forth.)

If you were to truly “blow up Hell,” or whatever, the quantum levels of the energy field would shift, completely disrupting all magical theory: A 3^rd level spell slot would no longer have the same amount of mystical energy. There might even be more or less discrete layers – i.e., spell levels – in the ley field.

Ley lines can be thought of as “cracks” in the skein of reality where this interplanar energy is pushing through into our plane of existence. They are a sort of obduction where magical energy enters the Material Plane, similar to how new crust is “pushed up” through ocean rifts. In any case, this means that a given ley line can be associated with one, some, or all nine of the energy fields (spell levels).

THE EVOLUTION OF MAGICAL THEORY

It used to be the case that each desmata had to be carefully customized to a specific flow of energy. (In other words, you had to prep a specific spell into each spell slot.) It was always known, however, that this was merely a theoretical limit: There were creatures with natural desmata, for example, who could use them to flexibly cast a variety of spells.

Some individuals were similarly known to be born with or later manifest natural desmata. In some cases, these desmata would become “active,” allowing these “natural spellcasters” to create variable magical effects without any formal training. However, this was an uncontrolled, dangerous, and incredibly unstable process. The spontaneous alignment of any desmata could go horribly awry. It might kill the spellcaster, burn out their magical ability, or, in rare cases, cause the desmata to become stuck “open” – basically spewing forth wild magic in a chaotic torrent.

These spontaneous spellcasters were basically walking cataclysms that could be unpredictably triggered at any moment. As a result, they were usually social pariahs. (People don’t like it when their neighbors randomly blow up.)

In the last century, however, significant breakthroughs in arcane theory made it possible for these spellcasters – or sorcerers – to, first, wield much greater control over which spells they could cast through their desmata (allowing them to learn specific spells instead of just manifesting random abilities) and, later, safely activate their dormant desmata in stable configurations.

Sorcerers stopped exploding. Some of the old prejudices remain, but over the past several decades they have mostly been reintegrated into society.

These theoretical breakthroughs also led to a greater understanding of the structure (or “weave”) of desmata. Studying the flexible desmata of sorcerers allowed other arcanists to perfect the design of non-specific desmata aligned to each ley field.

This was a revolution in magical theory!

The first flexible desmata to be perfected was actually for the third sphere of magic, but over the next decade arcanists rapidly perfected flexible desmata for each quantized field. You still had to study and master specific spell effects, but you no longer had to create one custom desmata for a fireball and a different custom desmata for a lightning bolt – you simply had a single flexible desmata of the third sphere which could be used to channel energy for either effect.

The insights gleaned from these new breakthroughs, however, also spilled into general field theory to arguably even greater effect. To fully understand that, however, we’ll first want to take a closer look at cantrips.

CANTRIPS: GENERAL FIELD THEORY

It has long been understood that in addition to the large, quantized ley fields, there is also a pervasive field of discordant, low-level mystic energy that appears to permeate all etheric and material matter. In older texts it is often referred to as the Discord. In bardic traditions it is sometimes referred to as the “unchorded song.” We’ll refer to as the general field.

The energy levels of the general field are so small that they’re generally “washed out” by the nine spheres of magic. As a result, the general field was first detected by elven arcanists studying the ambitus (or perimeter) of antimagic fields. (It is now widely recognized that certain arcane traditions of the beholder magi-lines had been aware of the general field for centuries before it was “discovered” by the elves, but, of course, beholders are infamously secretive about their arcane traditions, even with each other.)

The low energy of the general field severely limited the effects which could be created with it. In addition, the cumbersome desmata created to interface with the general field actually interfered with the far more useful desmata of the first sphere, reducing the number of such desmata that could be safely entangled!

However, the low energy and pervasive nature of the general field also made it considerably safer to manipulate. The general field spells – which became known as cantrips – were ideal for training new students in the arts of magic. The success rate (as opposed to the “messy death” rate) for apprenticeships soared, greatly invigorating arcane studies.

Huge tomes of cantrips were developed for apprentices, but due to the interference effects most magi abandoned them entirely once they were ready to master more powerful desmata, although it was not unknown for some to maintain a cluster of four or so of their favorite cantrips despite the sacrifice.

The next major breakthrough in cantrip theory came when Xylarthen perfected a spell form of the first sphere that could be used to flexibly channel any cantrip known to the caster. Ironically, the complexity of this form made it unsuitable for apprentices, but it did mean that more powerful magi who were nostalgic for their old cantrips no longer needed to maintain a disrupting cluster of cantrip desmata to practice them.

Hidden within Xylarthen’s cantrip spell, of course, was an alternative theory of flexible desmata (which, at this time, had not yet been perfected). This was widely recognized and any number of experimental arcanists began trying to expand the theory. The general belief was that it would be possible to create desmata of a higher level that could be used to flexibly cast less powerful effects: Just as a desmata of the first sphere could be used to flexibly cast cantrips, so a desmata of the fourth level, for example, might be able to channel spells of the third level. Various theories were promulgated, many of them featuring increasingly baroque arrangements of “resonance” (i.e., the idea that a fourth level desmata might be able to cast any second level spell, but not a third level one; or vice versa; or only a third and a first; and so forth). There was another school of thought which postulated that flexible desmata might be able to achieve stability within specific schools of magic.

All of these theories ultimately proved unsuccessful. There was a single desmata of the eighth sphere that could be used to cast spells of the fifth level and lower, but it proved to be incredibly unstable. After several spectacularly lethal disasters, the form was abandoned. The wizard Rary did eventually manage to construct a deserata of the third sphere that could be used to cast mixtures of lower level spells, but its use was highly specialized and he was never able to generalize the somewhat fluke discovery back into general principles.

The next true breakthrough in cantrip-related theory actually came from a completely different direction: Minor desmata were perfected which could be used to prepare cantrips powered by the “zero-level” field of mystical energy without disrupting higher level entanglements. These were not flexible desmata (each needed to be prepared for a specific cantrip), but it meant that arcanists could now continue using cantrips throughout their careers. They were also closer in theory to other desmata, making it easier for apprentices to transition from their early studies to more powerful spells.

When the theory of flexible desmata was later perfected, however, the old Xylarthenic theories were revisited. The new models made it clearer how Xylarthen’s cantrip spell had been using higher orders of magic to create a flexible construct that could channel energy from the general field. What was even more interesting, however, was that the new theories of desmatic creation suggested that it should be possible to create a flexible cantrip desmata which, due to the pervasive properties of the general field, would not lose its entanglement with the general field when used to cast a spell.

In other words, once a spellcaster had entangled their soul with the proper desmata, it was possible in theory to cast a limitless number of such spells.

It took some time to perfect, but that was more or less what the arcanists did, creating the order of magic as we know it today: Flexible desmata for spontaneously casting of spells of the first through ninth sphere and clusters of cantrip desmata that have no limit on often they can be used.

A MISCELLANEA

A few miscellaneous thoughts:

• The really interesting element of modern arcane theory is that there’s theoretically no limit to how much energy can be pulled from the general field. This means that a grand unified theory of magic would theoretically allow ALL magical spells to be powered by the general field and, therefore, cast without limit. At the moment, however, arcanists are limited to “solving” each spell individually. But each new spell that becomes a cantrip is a major achievement!
• Don’t get too excited: Elven arcanists will point out that the “grand unified theory” is always just twenty years away (for humans) or a hundred years away (for elves).
• Insofar as “magic” is the interface between a caster’s soul and the ley fields, psionics cannot be properly understood as “magic.” Psionic abilities are the result of manipulating, focusing, and multiplying the energy of the soul itself.
• Warlocks don’t have level-associated slots because they don’t actually entangle with the ley fields. They are instead directly entangled with their patron, which simply feeds them the ley energy. (This is why other arcanists often look at them with roughly the same terror that you might look at a high-capacity power line dancing around on the ground and shooting out sparks.)
• Divine mystic traditions used to be based on very different theories of how magic worked, allowing an interface with only seven of the spheres (although the particulars of that interface allowed them to create effects similar to arcane traditions using different ley fields). Over time, mystic theory has become more unified, with divine traditions tapping into arcane theory to create desmata that can entangle with all nine spheres.
• What hasn’t changed is that clerics are generally dependent on the connection to their god to create and entangle their desmata. This means most clerics are significantly less familiar with the fine details of arcane theory. These divine desmata, however, still have unique properties which make certain magical effects (like healing) possible that are still beyond arcane theory.
• There are magical “viruses” that can interface with desmata. Most only interface with spent desmata, but there are also some that can attach to entangled desmata. (These tend to be more dangerous.)

FURTHER READING
Spells: Parasites of the Mind
Scrolls: Bonds of Power