"What about the wand?" asks one red-robed apprentice who looks to be in his mid-teens. 

"Oh, silly me. That one doesn't contain any vis; it's just a pretty stick I use to point to things sometimes." There is a chorus of groans from the students. Alidade pauses. "...That was me being mean. But only a little bit; after all, vis is valuable, and many have tried to pass off mundane items as enchanted or vis-bearing. Distinguishing true concentrated Arts from fake is an important skill, which some of you would do well to cultivate." 

Alidade takes this opportunity to segue into the rest of the lesson, which is about common sources and uses of vis. 

Animal is mostly harvested from hard-to-domesticate magical beasts, and is used in Order of Sustenance rituals to create or enhance warbeasts and livestock.

Aquam can be found in water sources and (much more dangerous) certain parts of the sea. It is often used to supply water to villages or campaigning armies by creating springs.

Auram is needed for rituals that control the weather, which is problematic because it is usually harvested from natural storms. Much of the Empire's supply comes from isolated towers maintained by the Order of Aetherics.

Corpus is in high demand for longevity rituals and teleportation of troops. It is harvested from gnomoid bodies and objects long associated with them. 

"And blood magic?" one student inquires breathlessly.

"Yes, and blood magic, which can also produce Mentem or Vim."

The supply of Corpus has dwindled somewhat, Alidade continues, since Miezia limited the practice of blood magic to lawful executions (and reading between the lines, stopped slaughtering captured foes en masse), but it is recovering somewhat as the population grows and new sources are discovered.

Herbam is harvested from magical plants (or, in some cases, a sufficient quantity of mundane crops). As a vital component of the field rituals led by the Order of Sustenance, it is also in high demand, to the point where wars have been fought over access to forests suspected to contain sources. 

Ignem is famously volatile, and even more difficult than most Forms to acquire and store safely. Nonetheless, the Order of Aetherics has identified a few stable sources, including one in the heart of a volcano. It is mostly used in warfare, but also sees some use in enduring heating, cooling, and lighting effects. 

Imaginem is often drawn from particularly breathtaking spectacles, or traded from the fae at no small risk to the bargainer; Magus Centho, Head of the Order of Dreams, was promoted in part for his discovery of a way to harvest vis from silence in the Cave of Echoes. Originally popular for its value in beautification rituals, it finds other uses in the hands of Devisors and Dreamers. 

Mentem is the Form of minds and ghosts. The methods of its harvest are known mostly to members of Cognizance and Vision, as are most of its uses; but it is prized by Cognizance in particular for use in enhancement rituals. 

Terram vis is often found in mountains or caverns that have been touched by magic. It is useful in rituals to create, transport, and enhance arms and armor. 

Vim can be distilled from most magical auras in a labor-intensive process often assigned to otherwise unpromising apprentices. It is essential for many magical projects, including the making of most enchanted items. 

The Techniques can be harvested as well, but doing so is often tricky and requiring of ongoing effort by magi. Alidade tells the tale of a magus who harvested Creo from a forest by some long-forgotten ritual, only for an angry faerie to murder him and all his apprentices over the resulting stunting of growth within the wood. Also featured is the story of a monastery whose inhabitants swore a vow of chastity, the keeping of which could be harvested for Rego vis. One magus discovered that the productivity of the monastery increased the greater the temptation the monks faced, an incentive structure which led to unfortunate consequences for all concerned.

All five Techniques are highly sought-after; Creo for various enhancement and fertility rituals, Intellego for detection and spying, Muto for transformations and enchantments, Rego for teleportation rituals, and Perdo for war.

This wraps up the lesson. "The winner of the vis identification contest was Alexius Marcus of the Order of Viscera," Alidade concludes. "Please stay after class to receive your prize. You too, new student Alex," she adds. "I'd like to speak with you before you leave." 

"Oh wow!" The red-robed apprentice obeys. 

As the last students file out, Alidade produces a small, cracked gem from a pocket in her robes. "This is a mnemor lattice, or gemnory, a relic of Wennelthlim, recently found by a friend of mine." She hands it to Alexius. "It is flawed but functional; twice per day it can be held and activated by the command word lehashil, either to store a single memory or fact on which the holder is concentrating, or to retrieve a memory or fact so stored. It can only contain one piece of information at a time."

"Huh, that's fascinating. How does it work?"

"I don't know, unfortunately. Much knowledge has been lost, and not to gemnories. You might have better luck asking at the Isle of Wheels, I hear they managed to preserve some fragments of lore. I do know that it is a useful study tool; you can check how well your knowledge coheres by using it to remove a particular fact from your mind. If you can rederive the fact afterwards from what knowledge remains, it often sticks more strongly." 

"That seems really valuable! Are you sure you want to give it away?"

"Oh, it'll do more good in the hands of a conscientious student than in mine, I expect, and anyway I have a couple higher-quality ones to study now. Just promise to pass it along to a worthy student when it's no longer useful to you."

"Okay! I'll do that. Thank you, Magister Alidade." 

Alidade turns to Alex. "You did remarkably well for a new student, Alexandr Lustig. Do you have prior training, by chance?" Her tone is curious, not reproachful. 

"Not much in magic, my grandmother taught me a lot about medicine which let me realize it was an animal liver, beyond that my success here is from reading as much as I could find. If I can ask, those depictions of the elements and techniques you drew are different from the ones I've seen before is there a reason behind that?"

"I was wondering about that too." 

"Yes, those are the Gnostic symbols, which largely inspired the Miezan ones. I have a heated debate with a colleague over whether the changes were a deliberate adaptation or whether Miezan mage-scholars are just really terrible artists." Alidade grins. "Where are you from?" 

"Interesting." He would be inclined to assume intentionality some of the changes don't just look like simplifications or mistakes but he doesn't know enough yet. He wonders why she's asking about where he came from but answers without delay anyway. "I'm from Eriksmont in the Umbrica province."

Because then she'll know more things about him! 

"Ah, Umbrica, that explains the accent. You've come a long way to study at Grawtosh; I hope you find it enlightening. 

"Since you're joining us near the beginning of the season, you haven't missed much. I recommend a review of the Petronian Arts and the limits of magic in Chapters Two and Three of Fundamental Principles of the Arcane, unless you already feel comfortable with these topics. Next lesson will cover the basics of spellcasting. Any questions?" 

"I'll review those chapters as soon as I can. Is the instruction on spell casting just theoretical or are there small spells we'll be able to cast before the ritual?"

"Not all of my students are Gifted, so our ability to experiment as a class is limited. I typically pair up those who have been Opened to the Arts with those who have not, so that they can try some very basic magical exercises. We won't be doing any formulaic spells, as even the weakest of those usually take longer than a few hours to learn.

"If you've had any practice with Arts before, you might be able to try some of the spontaneous or ceremonial exercises without having been formally Opened, but I'd recommend sticking to those Arts you are familiar with."

"I think I might have managed a little bit of magical healing," at least that's one guess he has for the higher attributes in Creo and Corpus, "but nothing dramatic enough to know for sure. If I'm right that means I have some inclination towards Creo and Corpus."

"Oh, good, healing is always useful. I have a few good exercises using those Arts." 

"Neat, I'm looking to specialize along the same lines. Mentem, too. "