Mana is the Element V among the Four Elements, corresponding to aether in Plato's theory of five elements. It greatly affects the potency of Magic released by Being.
Mana, like aether, is everywhere, and can therefore be perceived by beings with the ability to manipulate it. The strength of this perceptive ability has no direct relationship with one's Mana Capacity (see below) — though for Sorcerers, there is a positive correlation, along with a unique mechanism. This means most magic leaves traces — traces that can be sensed by mages. Methods such as //Tracery and the Cysindera Test also exist for visualizing the presence of Mana.
Generally speaking, unless the spell was extremely large in scale, traces become very weak one week after being cast. For mages without strong Mana insight, they must carefully and actively sense to detect them. This is because free Mana tends toward equilibrium, naturally flowing from areas of high concentration to low concentration like a gas. Even so, due to Mana's adhesive effect on the surface it was cast upon, even after several decades, as long as the surface has not been treated with a Suppressant such as Siment Flower, traces of Mana will still remain.
Mana Capacity and Voiceprint
Beings are containers for Mana; Mana Capacity refers to how much Mana a Being can store. As stated above, Mana tends toward equilibrium — so the principle that "Beings are containers for Mana" actually means that Beings have a higher Mana Potential. When the Mana inside a Beingis low, surrounding Mana spontaneously flows in. From this we can see that Mana Capacity — how much Mana can be stored — is mainly determined by a Creation's Mana Potential (because once the internal Mana concentration reaches a sufficiently high value, it forms equilibrium with the outside; Mana still flows, but inflow and outflow rates are equal).
Sorcerers are born with higher Mana Capacity, partly because they are born with a considerably high Mana Potential (fully formed before adulthood), and partly because Sorcerers can freely control the flow of Mana in and out of their bodies — underloading, full-loading, or even overloading. This ability grants many benefits, including but not limited to:
Restoring Mana extremely quickly, as if inexhaustible
Providing a massive amount of Mana for a single spellcast through overloading when necessary
Making it difficult for others to detect a Sorcerer's presence through Mana
Regarding the third point: it is necessary to elaborate on what Mana — the substance corresponding to aether — actually is. First, Mana possesses divisibility. This means you can think of Mana as an enormous number of extremely small fictional particles, like molecules, but without actual volume. This allows Mana to be arranged into certain structures, just as molecules can be. Without external forces, structured Mana tends to return to a state of disordered diffusion. To manipulate Mana, mages typically arrange the Mana within their bodies according to personal habits (so-called Manipulate). This arrangement is roughly consistent across all intelligent beings — the closer two Beings' Phase are, the more similar their methods of arranging Mana tend to be. This method is like the genome of Mana, which we call a "Voiceprint" — all beings have genomes, and those of the same species are more similar, but each individual is unique. (If you don't understand what a genome is, just think of fingerprints.) The act of identifying others by sensing Mana is actually accomplished by distinguishing the still-structured Mana that a Being emits during its exchange of Mana with the surroundings. In casual conversation, this arrangement is sometimes referred to simply as "Mana." (e.g., Shiki Takaaki‘s Grace-IV: "Ferdinand couldn't tell who the visitor was, but he could distinguish that non-human Mana from hundreds of meters away.") The "Mana residue" mentioned in the Cysindera Test and similar contexts actually refers to structured Mana — since Mana is ubiquitous, verifying whether Mana exists is as pointless as verifying whether there is air on Earth. The gap between this casual "Mana" and the technical term "Voiceprint" is akin to the scientific information gap in the real world — if you understand science well enough, you can comprehend the origins of everyday phenomena as well as their academic names.
However, Sorcerers do not need to arrange their Mana in order to wield it. Even the Mana that radiates from their bodies is disordered and scattered, meaning it is very difficult to recognize it as Mana emanating from a Being, and thus to become aware of that being's existence. Even if a Sorcerer is already very close to you — meaning you are already in an area of relatively high Mana around them — they can still prevent you from detecting them by suppressing the exchange of Mana between themselves and the outside world.
The name "Voiceprint" comes from the experiment in which it was discovered: a method that coerced Mana into vibration, then visualized the vibration into a pattern.
How Do Beings Manipulate Mana?
Beings are containers for Mana, but the distribution of Mana within these containers is not uniform. This distribution generally follows the principle of use it or lose it — concentrating most heavily at the extremities of the limbs, particularly the hands.