How the Arts are reckoned
Each part of the world has its own element, of which there are five; earth, water, fire, air and the spirit. In the West our magic derives from the element of water, which itself is divided into four Arts; Druidry, Enchantment, Sorcery and Illusion. – Gideon (from his first lesson to Caleigh).
With the exception of Summoners, no mages use an element in its pure form. All known forms of magic are a combination of the Base Element, which is universal to their culture and their personal Affinity Element. The mage in question will always be more inclined towards spells that include aspects of these two elements whether that be in a literal or metaphorical sense.
The Base Elements
Each part of the world and the culture within it will be tied to a Base Element; in the Western Lands it is Water, in the Norse Lands it is Earth, in the Imperium it is fire, In the East it is Air and the Spirit finds its home in Heartlands from which all mankind originated.
The Affinity Elements
Each mage will have an additional Element that combines with the Base Element to decide what their Art will be.
Crossover between Arts
Yes. As I said before, my Art is part fire so I have a familiarity with your fire magic, most particularly with the magic of fire and water, which Euphemius terms the magic of the moon. When allies of mine learnt of the murder of the Priestesses of Venus there was a brief opportunity to capture their lore before it fell into the wrong hands – Callisto
There will be some spells that can be learnt from all the Arts that share at least one Element with the mage. That said, it takes a mage of exceptional talent to be able to use these spells effectively. Most of the magically gifted can only perform magic from one discipline within their own Art.
The difference between an Art and a Discipline?
The Art is the branch of magic the mage uses and the Discipline is the particular group of spells and skills within the Art. There are always at least three Disciplines per Art.
Elemental (Common) Magic
But don’t think the elements of magic stop with water, fire, air and earth. There is energy and substance and the flow of time as well, but before I start sounding like Gideon I’ll just say there’s plenty to wizardry even without an Art – Vaughn
Common elemental magic is distinct from the Arts in that it is magic that can be performed by any mage in any part of the world. These are the universal concepts that all mages can appreciate.