The exact term for each type varies somewhat from source to source, though these four are now the most usual. Most of these beings are found in folklore as well as alchemy; their names are often used interchangeably with similar beings from folklore. The sylph, however, is rarely encountered outside of alchemical contexts.
The basic concept of an elemental refers to the ancient idea of elements as fundamental building blocks of nature. In the system prevailing in the Classical world, there were four elements: fire, earth, air, and water. This paradigm was highly influential in Medieval natural philosophy, and Paracelsus evidently intended to draw a range of mythological beings into this paradigm by identifying them as belonging to one of these four elemental types.
In mysticism, magic and alchemy, an elemental is a creature (usually a spirit) that is attuned with, or composed of, one of the classical elements: air, earth, fire and water. The elements balance each other out through opposites: water quenches fire, fire boils water, earth contains air, air erodes earth. The concept of elementals seems to have been conceived by Paracelsus in the 16th century, though he did not in fact use the term "elemental" or a German equivalent. Paracelsus gave common names for the elemental types, as well as alternate names, which he seems to have considered somewhat more proper. He also referred to them by purely German terms which are roughly equivalent to "water people," "mountain people," and so on, using all the different forms interchangeably. The Paracelsian elementals were:
|Translated Common Name||Proper Name||Element|
Of these names, gnomus, undina, and sylph are all thought to have appeared first in Paracelsus' works, though undina is a fairly obvious Latin derivative. The other names are traditional terms, though the Paracelsian usage is thought to be novel.
He noted that undines are similar to humans in size, while sylphs are rougher, bigger, longer, and stronger. Gnomes are short, while salamanders are long, narrow, and lean.
In his influential De Occulta Philosophia of the same period, Heinrich Cornelius Agrippa also wrote of four classes of spirits corresponding to the four elements, though he did not give special names for the classes. Agrippa did however give an extensive list of various mythological beings of this type, although without clarifying which belongs to which elemental class. Like Paracelsus, he did not use the term "elemental spirit" per se.