This is a small snippet of history about this world - but pay attention. There is more than just lore or history in here; while I call it out explicitly here, I may not be so transparent in the future. This not only explains how magic works, but also tells a little about a fellow with some magical artifacts...
Magic is a strange thing. Many believe that having the right ingredients and speaking the correct words are enough to cast a spell; this is a very useful analogy, and yet it is entirely false. Magic is not science. Machines cannot cast magic; they may be able to wield magic that has been cast upon them, but alone, they will never cast even the simplest of spells. The key lies in ancient, deep magic - spells so powerful that a man can change the shape of the universe merely by thinking about them.
When a mage learns a new spell, he does not simply calculate ingredients and wave his hands. While that may be good enough for a cake, it would never work for a spell. Rather, the mage studies the spell and forms it in his mind; once it is formed, he writes it down in his own cryptic way. In writing the symbols of his choice, he casts a spell, deep magic which gathers his thoughts and embeds the very essence of the spell in the page. From there, the mage may draw the essence of the spell out again as often as he wishes.
Clerics and those who call upon gods for their spells use a different form of storage. Rather than keeping the essence of spells in a great tome, a cleric's deity holds that essence, and releases it when the cleric requests. Even so, a cleric may research a new spell, and transfer its essence to their deity through devout prayer. Those who inherit magic, like the Fae, already have the spells woven within themselves; they have no need of gods or books, for they can call out the spells as easily as speaking.
If one were able to understand, to truly know the deep magic of writing spells, one would be able to capture that deep magic on a page, and from there could instantly and permanently capture any spell in existence, be it simple illusions or earth-shattering events. And indeed, all motion of the world stems from magic; the magic of bubbling streams, of life and death, of secrets and dreams. With that single spell, Man could rewrite the world.
Of course, no mortal mind could grasp such a spell; even the various deities could never hope to understand it, and the world is a better place for it. Deep magic is tied to the essence of the universe; capturing even a part of it begins to fray the strands that hold it together. Using deep magic pulls those strands, and using deep magic without without fully understanding how all deep magic works together will tear and disfigure, snagging and ripping the fabric of the universe.
Artemis the Scholar
And yet... one man understood. Through his life, Artemis had a singular focus: study. Unlike his fellow mages, Artemis yearned to understand understanding, to learn how to learn, to study studying. Rather than studying great tomes, he studied those who did. Throughout his life, he gained spells and knowledge that prolonged his life, accelerated his actions, and improved his memory, but those were nothing compared to what he knew awaited him. He treated spells as a peasant treats a plow; tools, and nothing more. He had no wonder for such trifles. Instead, he scryed on books and listened to thoughts, and watched the strange machinations of Deep Magic, always studying and learning. For a thousand years, he studied.
Finally, his life's work was brought to completion. He stepped out of the bonds of mortality, of time itself, and spoke; each word that fell from his lips was a Word of Power, and with them he formed the first Sentence of Power ever spoken. Only from outside time could he utter such a phrase; on a mortal plane, it would rend earth and flesh alike. From his place outside of time, he found the end of his quest: Knowledge. As a true scholar, he recorded it in a book, naught but a few deft scribbles before he laid aside his pen and returned to our plane. His life's work complete, he returned to an ordinary life, an ordinary man in an ordinary world. He left his book in the outer plane; a book written in Words of Power would surely destroy the world in which it rests. However, other items in his possessions can still be found: the Pen of Artemis, far mightier than a sword; the Cloak of Artemis, stylish, warm, and enlightening; and most powerful of all, the Staff of Artemis, a rod imbued with power granted by that unimaginable by all but one.