In magick many beliefs follow the idea of the elements. In basic it is the things or energy that make up all other things. Different beliefs have slightly different elements or properties but for there are usually many similarities between them. Understanding of these elements aids in many of these beliefs spells and rituals. Im going to start with the Japanese system (since I know it better than most) and either talk about others at the end or on another day.
These are based primarily of Japanese Buddhist philosophy. There are 5 elements that make up all things both internal and external. of these their are 4 Primary elements and 1 That is both a part of the 4 yet something much more.
The four primary elements are the easiest to explain and see how it works. Ill list there more common name first then what that element truly symbolizes. Ill explain each and what that element makes within the body. As an addition ill try to explain how this element can be used martially and through spellcraft.
Water- While this is called water it can actually stand for any liquid or fluid. Fluidity is the most important thing to this element. Constant motion yet still a semblance of unity. In terms of physics this would be liquids but once it turned gas or solid it would no longer be this element. Blood is commonly associated with this element. In martial arts someone who understands and utilizes this element will control momentum as if he was water in a glass. When a strike comes it pulls back only to counter with equal strength. In spellcraft this element is important for matters of control. Feeling the energy flow both within and outside of yourself. Directing this flow in many ways is controlling this element.
Earth- Like water this element represents much more than earth. In many ways it is all solids. Resilient strength both physically and of will is a mainstay of this element. Bone is a common representation of this element. A martial artist who understands this element can move there body in such a way that it is resilient to force. It can be difficult to push or manipulate the martial artist body. In spellcraft it is an embodiment of willpower. Standing firm in your use of energy to have the desired affect.
Air- All things of a gaseous nature. This element is all around us but often goes unseen. Where water maintains a unity this element does no such thing. It can spread anywhere and everywhere. In the body our respiratory system is a common depiction of air. A martial artist using air strike from uncommon directions or moves sporadically in way that are hard to detect. In spellcasting air is often hard to appreciate. It is a source of power all around being influenced by your will.
Fire- Perhaps the hardest of the primary elements to explain. Fire is all things energy. It is a spark of life and passion. Often it is associated with heat. In the body our heart is often used to express fire. are martial artist who knows the fire element may strike fast and hard. It is a direct force. In spellcasting it is also a direct force. It flows from you into what your doing empowering it.
The most important thing to remember is that all of these elements are connected. Without each of them you are doomed to fail. A body will not operate, a martial artist will not win, nor will a spell be cast effectively. The 5th element touches each of them but also is separate from them. It is everything and it is nothing.
Akasha aka void, spirit. This element is the hardest to represent as it is all the primary elements above and more. In a way it represents the soul or unity of self. Our senses are tied to the akasha. In our body the eyes, mouth, ears, and mouth are common representations. A martial artist who understands the akasha can understand himself and his opponent. It will lend foresight in a fight. In spellcasting the akasha often represents a sixth sense. Clairvoyance and other things like it are tied to the akasha.
This is just one elemental system. Let me know if you have questions and feel free to add something you think I missed.
Be Well
You know, I really like the fact you wrote about the elements based on Japanese Buddhist philosophy rather than the usual 'traditional' uses. Really really like it :)