Like the physical shields used since antiquity, psychic shields can be manufactured from different 'materials'. The most common materials used in psychic shields of modern magicians correspond to the classical four elements that are referenced in alchemical texts from the late Medieval and Renaissance periods of European history, which are in turn rooted in the texts of antiquity from the Roman and Greek cultures. The use of these materials is one that is common for two reasons. They are easiest for practitioners to access due to the relatively unbroken line of connection to them through out Western culture and they are based in things that are easily accessible to our understanding and therefore more 'real' to us than other psychic materials that can be used.
The easiest of the four elements that we can access is that of Earth. In all places about the globe where people live, they live upon the Earth. The solidity of the Earth and the strength of how it is perceived varies to some degree from region to region based upon the geological conditions. In a region where sand is the dominant land form, the element of Earth is more fluid than it is in a region where the dominant land forms are rocky, such as in a mountainous region. In both places, however, the element of Earth tends to be more fixed than the other three elements. A shield which is constructed drawing upon the energies of Earth will be solid and less porous than a shield constructed from the other elemental energies. It will, however, be such that the caster must apply greater effort to manipulate the shield after it has been established. Also, shields that are based strictly in Earth energy can be worn down eventually through the application of magic that is based in the Water element.
The element of Water is the second densest of energies. Almost as prevalent as Earth, Water energy is highly mutable and varies widely in how it can be applied, where as Earth is generally a fixed element. Just as the water that is physically upon the globe has different depths and qualities, the Water elemental energy can range from a shallow highly permeable type of energy form to a depthless and fearsomely powerful energy form to a brittle solid energy form that is not permeable to most any other energy forms. A shield constructed from Water's elemental energy is effective against magic based in Earth elemental energy and of mixed results with magic that is based in Air energy. Fire energy is extremely effective against Water and depending upon the 'depth' of your shield, it can nullify the Water energy's protective effect fairly quickly.
Fire energy (which includes electrical energy via the Western four elements classification system) is considered highly active. Fire energy is a bit harder to access with out props (i.e. a candle, fire, etc.) because it is not as immediate before our eyes and senses. It tends to be the most challenging of elemental energies to control because it is extremely mutable and volatile. A shield based in Fire energy is susceptible to Water and Earth energies, as they will quench or smother the Fire energy. It is, however, the elemental energy that can be strengthened when another element is applied against it, Air. A Fire based shield is permeable to Earth energy and not well suited for defense against Water based elemental magic for reasons stated above. It is, however, excellent for defense against Air magic because the application of Air elemental magic will strengthen and add more 'power' to the shield.
The element of Air is the lightest of the energies in this system. Air is the second most accessible of the energy forms because it is present everywhere. Against Earth magic, the shield based in Air energy is useless. It is equally ineffective against Water magic. This is because it is the most permeable of the energies that a magician can use. It is possible to use a shield based in the element of Air against Fire magic, but only for a limited time because the Air energy will increase the potency of the Fire magic over time.
Constructing an elemental shield is a process that is virtually identical to that of the basic mirrored sphere shield. Simply envisioning one's outer aura surrounded by the element in as great or little of a thickness that you require serves to create this shield. Earth shields are effective for absorbing and grounding magical and psychic attacks directed against the defender. Water shields are effective for deflecting and grounding attacks. Fire shields absorb attacks and deflect them. Air shields deflect attacks and can function to obfuscate the defender from the attacker.
Each shield used alone is somewhat effective. They are most effective, however, when used in concert with each other. Generally, elemental shields are used as an outer layer to the mirrored sphere. A nested shield effect can be done by visualizing the shields stacked upon each other with a space between them. Shields that are paired with the ones they are most vulnerable are more effective because the outer shield serves as a filter for the energy they are vulnerable to. Thus, a magician may use a Fire shield as their outermost shield to absorb and filter out that element's energy to prevent it from damaging the Water shield beneath it.
The use of nested shields is a step towards creating a 'castle' with a 'moat' about it. This technique will be discussed in the next article.
1. As with other forms of psychic exercise and spell craft, the ability to maintain concentration upon the goal of your exercise is paramount. It is this focused concentration and the ability to vividly visualize the end goal in a fashion that incorporates as many of the senses as possible that directs one's personal psychic energy into the 'structure' of the end result.
2. I am using the term magicians to encompass all people who engage in the magical arts, amongst which psychic ability is classed. Other authors may use the terms 'mage' or 'occultists.' I have in past articles and consider all three terms to be interchangeable. Do not confuse the term magician in this discussion with the stage magicians of the entertainment industry, they are only indirectly related.