The ancient metaphysical science/mystical art of manipulating and altering matter by using natural energy. This act is known as "Transmutation" and its sequence is usually described as:
- Comprehension - Understanding the inherent structure and properties of the atomic or molecular makeup of a particular material to be transmuted, including the flow and balance of potential and kinetic energy within.
- Deconstruction - Using energy to break down the physical structure of the identified material into a more malleable state so as to be easily reshaped into a new form.
- Reconstruction - Continuing the flow of energy so as to reform the material into a new shape.
The proper application of this craft requires not only a full understanding of chemistry and ancient alchemical theory, but also a sort of natural talent towards recognizing and manipulating the physical objects with energy, which require uncommon levels of intelligence and aptitude. Those remarkable individuals capable of studying and practicing alchemy are known as "Alchemists".
There are many paths by which alchemists can transmute the various substances of the world, with some alchemists being said to transmute by way of the Four Classical Elements (Water, Earth, Fire and Air) and some by way of the Three Essential Principles (salt, sulfur and mercury), but the basic tenet at the very foundation of all alchemy is that of Equivalent Exchange.
The mystical practice of alchemy to create objects out of raw matter or turn one object into another is widely believed to be capable of anything - indeed alchemy is often viewed as magical or miraculous by those unfamiliar with the craft - but it is a science and as such is subject to certain laws and limitations, all of which fall under the concept of Equivalent Exchange: "In order to obtain or create something, something of equal value must be lost or destroyed."
In standard practice, Equivalent Exchange is separated into two parts:
The Law of Conservation of Mass which states that energy and matter can neither be created from nothing nor destroyed to the point of elemental nonexistence. In other words, to create an object weighing one kilogram, at least one kilogram of material is necessary and destroying an object weighing one kilogram would reduce it to a set of parts, the sum of which would weigh one kilogram.
The Law of Natural Providence which states that an object or material made of a particular substance or element can only be transmuted into another object with the same basic makeup and properties of that initial material. In other words, an object or material made mostly of water can only be transmuted into another object with the attributes of water.
Since the alchemical forces being manipulated are not human in origin, but of the world as a whole, the consequences for attempting to bypass the Law of Equivalent Exchange in transmutation are not merely failure and cessation. When too much is attempted out of too little, what occurs is called a Rebound, in which the alchemical forces that are thrown out of balance on either side of the equation fluctuate wildly of their own accord in order to stabilize themselves - taking or giving more than was intended in often unpredictable and catastrophic ways such as accidental mutation, serious injury or death.