I realized while I was writing this that I started to stray away from what was canon for Dresdenverse magic. I denoted these in green.
Foci Expanded
Trying to direct raw magic with the force of one's will alone is much like trying to lift a mountain with one's bare hands. A Focus works much like a lever and fulcrum, allowing much greater effects to be achieved with less effort. As was explained earlier, foci work in two ways: they either provide an aid for visualization, physically channel energy, or both.
Foci that aid in visualization can take the form of any symbol that is meaningful to the wizard. Hand movements or other bodily gestures can mimic or direct the movement of magical energies. Taoist wizards, or Fang Shih, have honed this practice to a fine degree with such techniques as the elaborate movements of Tai Qi.
Language, written or spoken, is also a powerful tool for wizards in directing magic. The specific language chosen for magical workings is usually not one the wizard speaks in their day-to-day life. This serves two purposes. For wizards who practice their magic within the context of their faith it raises magical workings to a sacred level, separating it from mundane things. It also serves to insulate the Form of the spell from extraneous associations that everyday words have in the wizard's mind. These extraneous associations threaten the integrity of the spell's image and usually result in wasted energy being dumped directly into the mind of the wizard. This is dangerous to one's sanity.
Foci that serve as physical channels for magic are constructed from materials that are attuned to different kinds of energies. Occult lore from cultures around the world describes the various properties of different stones, wood, metals, etc. See your copy of "Five Magical Materials" for more information. The materials used as permanent Foci tend to be of sturdy materials in order to withstand the stresses of channelling energy. The human body can technically be used to channel magical energy, but this can be dangerous. The wizards of those cultures that practice this focus method adhere to strict regimens of exercise, diet, and asceticism in order to attune their bodies to the flow of magical energy and prevent injury.
Enchantment and Alchemy
A wizard may sometimes wish to store Energy in the Form of spells for later use. This is done through the practices of Enchantment and Alchemy. Enchantment is the process by which a durable Focus is constructed in such a way that Energy is stored within its physical matrix instead of flowing out immediately. This Energy can later be released in response to a specific trigger, flowing out in the Form described by the design of the item. Alchemy works on the same principles, but doesn't require the same quality of materials and is, consequently, much shorter lived. The Form of the spell cast into an alchemical potion or ointment is anchored by reagents that bring the spell's effect to mind using all five physical senses, the mind, the heart, and the soul. The Energy is provided by the alchemist upon creation of the potion. The trigger for the release of the spell is ingestion or application of the substance.
The Laws of Sympathy and Contagion
"Once a part of something, always a part of something."
"As above, so below."
"Like produces like."
These homilies, and many others like them, speak of the interconnectedness of the universe. Wizards have known for millenia that a small part of something holds knowledge about, and a connection to, the whole. It is only recently that modern science has discovered things like genetics and quantum physics. This interconnectedness is utilized by wizards most often in thaumaturgy, when the small sample of an object is used as a conduit to affect the entire object. In the same way someone's True Name, spoken from their own lips, can serve as a conduit to affect them thaumaturgically. It is as much a piece of their mind and soul as a drop of blood is a piece of their body. Always guard your True Name and never seek another's True Name or you may risk being a victim of a violation of the Fourth Law. Worse, you may be tempted to break it yourself.
