Many philosophies and worldviews have a set of classical elements believed to reflect the simplest essential parts and principles of which anything can consist or upon which the constitution and fundamental powers of everything are based. Most frequently, classical elements refer to ancient concepts which some science writers compare to the modern states of matter, relating earth to the solid state, water to liquid, air to gaseous and fire to plasma. Historians trace the evolution of modern theory pertaining to the chemical elements, as well as chemical compounds and mixtures of chemical substances to medieval, and Greek models. Many concepts once thought to be analogous, such as the Chinese Wu Xing, are now understood more figuratively.
In classical thought, the four elements earth, water, air, and fire frequently occur; sometimes including a fifth element or quintessence (after "quint" meaning "fifth") called aether in ancient Greece and akasha in India. The concept of the five elements formed a basis of analysis in both Hinduism and Buddhism. In Hinduism, particularly in an esoteric context, the four states-of-matter describe matter, and a fifth element describes that which was beyond the material world. Similar lists existed in ancient China and Japan. In Buddhism the four great elements, to which two others are sometimes added, are not viewed as substances, but as categories of sensory experience.
Cosmic elements in Babylonia
In Babylonian mythology, the cosmogony called Enûma Eliš, a text written between the 18th and 16th centuries BC, involves five gods that we might see as personified cosmic elements: sea, earth, sky, wind. In other Babylonian texts these phenomena are considered independent of their association with deities, though they are not treated as the component elements of the universe, as later in Empedocles.
Aristotelian elements and qualities
The ancient Greek belief in five basic elements, these being earth (γῆ ge), water (ὕδωρ hudor), air (ἀήρ aer), fire (πῦρ pur) and aether (αἰθήρ aither), dates from pre-Socratic times and persisted throughout the Middle Ages and into the Renaissance, deeply influencing European thought and culture. These five elements are sometimes associated with the five platonic solids.
Sicilian philosopher Empedocles (ca. 450 BC) proved (at least to his satisfaction) that air was a separate substance by observing that a bucket inverted in water did not become filled with water, a pocket of air remaining trapped inside. Prior to Empodocles, Greek philosophers had debated which substance was the primordial element from which everything else was made; Heraclitus championed fire, Thales supported water, and Anaximenes plumped for air. Anaximander argued that the primordial substance was not any of the known substances, but could be transformed into them, and they into each other. Empedocles was the first to propose four elements, fire, earth, air, and water. He called them the four "roots" (ῥιζὤματα, rhizōmata).
Plato seems to have been the first to use the term "element (στοιχεῖον, stoicheion)" in reference to air, fire, earth, and water. The ancient Greek word for element, stoicheion (from stoicheo, "to line up") meant "smallest division (of a sun-dial), a syllable", as the composing unit of an alphabet it could denote a letter and the smallest unit from which a word is formed. A similar alphabetic metaphor may be the origin of the equivalent Latin word elementum (from which the English word comes), possibly based on the names of the letters 'l', 'm', and 'n', though the validity of this idea is debated.
In his On Generation and Corruption, Aristotle related each of the four elements to two of the four sensible qualities:
- Fire is primarily hot and secondarily dry.
- Air is primarily wet and secondarily hot.
- Water is primarily cold and secondarily wet.
- Earth is primarily dry and secondarily cold.
One classic diagram (above) has one square inscribed in the other, with the corners of one being the classical elements, and the corners of the other being the properties. The opposite corner is the opposite of these properties, "hot – cold" and "dry – wet".
Aristotle added a fifth element, aether, as the quintessence, reasoning that whereas fire, earth, air, and water were earthly and corruptible, since no changes had been perceived in the heavenly regions, the stars cannot be made out of any of the four elements but must be made of a different, unchangeable, heavenly substance.
The Neoplatonic philosopher, Proclus, rejected Aristotle's theory relating the elements to the sensible qualities hot, cold, wet, and dry. He maintained that each of the elements has three properties. Fire is sharp, subtle, and mobile while its opposite, earth, is blunt, dense, and immobile; they are joined by the intermediate elements, air and water, in the following fashion:
The elemental system used in Medieval alchemy was developed primarily by the Persian alchemist Jābir ibn Hayyān and rooted in the classical elements of Greek tradition. His system consisted of the four Aristotelian elements of air, earth, fire, and water in addition to two philosophical elements: sulphur, characterizing the principle of combustibility, "the stone which burns"; and mercury, characterizing the principle of metallic properties. They were seen by early alchemists as idealized expressions of irreducibile components of the universe and are of larger consideration within philosophical alchemy.
The three metallic principles—sulphur to flammability or combustion, mercury to volatility and stability, and salt to solidity—became the tria prima of the Swiss alchemist Paracelsus. He reasoned that Aristotle’s four element theory appeared in bodies as three principles. Paracelsus saw these principles as fundamental and justified them by recourse to the description of how wood burns in fire. Mercury included the cohesive principle, so that when it left in smoke the wood fell apart. Smoke described the volatility (the mercurial principle), the heat-giving flames described flammability (sulphur), and the remnant ash described solidity (salt).
A Greek text called the Kore Kosmou ("Virgin of the World") ascribed to Hermes Trismegistus (the name given by the Greeks to the Egyptian god Thoth), names the four elements fire, water, air, and earth. As described in this book:
And Isis answer made: Of living things, my son, some are made friends with fire, and some with water, some with air, and some with earth, and some with two or three of these, and some with all. And, on the contrary, again some are made enemies of fire, and some of water, some of earth, and some of air, and some of two of them, and some of three, and some of all. For instance, son, the locust and all flies flee fire; the eagle and the hawk and all high-flying birds flee water; fish, air and earth; the snake avoids the open air. Whereas snakes and all creeping things love earth; all swimming things love water; winged things, air, of which they are the citizens; while those that fly still higher love the fire and have the habitat near it. Not that some of the animals as well do not love fire; for instance salamanders, for they even have their homes in it. It is because one or another of the elements doth form their bodies' outer envelope. Each soul, accordingly, while it is in its body is weighted and constricted by these four.
According to Galen, these elements were used by Hippocrates in describing the human body with an association with the four humours: yellow bile (fire), black bile (earth), blood (air), and phlegm (water).