From ancient civilizations to modern day, the colors and symbols of the four elements have represented the different aspects of nature and the forces of energy in our world. The idea that these four elements—Earth, Water, Air, and Fire—made up all matter was the cornerstone of philosophy, science, and medicine for two-thousand years.
Historians believe that as early as the 8th century BCE, ancient Greek philosophers of the Archaic period began formulating theories of the four classical elements. Although the Greeks believed that the four elements were unchanging in nature, everything was made up of these elements, held together or pushed apart by forces of attraction and repulsion, causing substances to appear to change. This is similar to what really happens with elements and all molecules at an atomic level.
To the ancient Greeks, the four elements described not only physical manifestations of the material world but essential qualities of human nature as well. For instance, the Earth, solid and substantial, was associated with the physical and sensual aspects of life. Water, flowing and ever-changing, denoted emotion and empathy. Air was not only the air we breathe and the atmosphere, but signified the mind, intelligence, and inspiration. Fire meant the Sun and flame; it also indicated creative passion and destructive zeal.
Before digging into the myriad of aspects of how the Four Elements in fact shape and affect our life, this is the back-story of how they originated.
The Atmosphere, History of
In the first 500 million years of Earth's history, a dense atmosphere emerged from the vapor and gases that were expelled during degassing of the planet's interior. These gases may have consisted of hydrogen (H2), water vapor, methane (CH4), and carbon oxides. Prior to 3.5 billion years ago, the atmosphere probably consisted of carbon dioxide (CO2), carbon monoxide (CO), water (H2O), nitrogen (N2), and hydrogen (H).
The hydrosphere was formed 4 billion years ago from the condensation of water vapor, resulting in oceans of water in which sedimentation occurred. The most important feature of the ancient environment was the absence of free oxygen. Evidence of such an anaerobic reducing atmosphere is hidden in early rock formations that contain many elements, such as iron and uranium, in their reduced states. Elements in this state are not found in the rocks of mid-Precambrian and younger ages, less than 3 billion years old.
One billion years ago, early aquatic organisms called blue-green algae began using energy from the Sun to split molecules of H2O and CO2, and recombine them into organic compounds and molecular oxygen (O2). This solar energy conversion process is known as photosynthesis. Some of the photosynthetically created oxygen combined with organic carbon to recreate CO2 molecules; the remaining oxygen accumulated in the atmosphere. As oxygen in the atmosphere increased, CO2 decreased.
High in the atmosphere, some oxygen (O2) molecules absorbed energy from the Sun's ultraviolet (UV) rays and split to form single oxygen atoms, which combined with remaining oxygen (O2) to form ozone (O3) molecules that are very effective at absorbing UV rays. The thin layer of ozone that surrounds Earth acts as a shield, protecting the planet from irradiation by UV light.
The amount of ozone required to shield Earth from biologically lethal UV radiation, wavelengths from 200 to 300 nanometers (nm), is believed to have been in existence 600 million years ago. At this time, the oxygen level was approximately 10% of its present atmospheric concentration. Prior to this period, life was restricted to the ocean; the presence of ozone enabled organisms to develop and live on the land. Ozone played a significant role in the evolution of life on Earth, and allows life as we presently know it to exist.
Today, the atmosphere of the Earth may be divided into several distinct layers: troposphere, stratosphere, ozone layer, mesosphere, and ionosphere. The troposphere is where all weather takes place; it is the region of rising and falling packets of air. Above the troposphere is the stratosphere, where air flow is mostly horizontal.
Above the stratosphere is the mesosphere where the temperature drops to about -100°C. Above that is the ionosphere, or thermosphere, where many atoms are ionized. The ionosphere is very thin, but it is where the aurora takes place; it is also responsible for absorbing the most energetic photons from the Sun, and for reflecting radio waves, thereby making long-distance radio communication possible.
And then there was Fire
Logically, we may assume there was once a time when man had no fire; however, very early he must have become acquainted with fire derived from natural sources, and made use of it, for no remains of man's art show him without fire as his companion. Much later in the scheme of things he invented processes for making fire artificially.
The discovery of fire, or more precisely the controlled use of fire, was a necessity. The control of fire by early humans was a turning point in the cultural aspect of human evolution, allowing humans to cook food, as well as obtain warmth and protection. Making fire allowed the expansion of human activity into the colder hours of the night, and provided protection from predators and insects.
Stone Age man used fire to make tools 50,000 years earlier than scientists thought. Early modern humans at 72,000 years ago were using carefully controlled hearths in a complex process, known as heat treatment, to heat stone and change its properties.
With the acquisition of fire came the problem of preserving it; interesting examples of the ingenuity of man were presented. First, the fire was buried; preserved in the ashes of the fire itself. Next, a type of slow-match or fire-stick was developed, and later, when man worked with metals, the curfew, or “fire-cover” was invented.
Symbolic and superstitious uses of fire have been common. At an early period, altar fires were kept sacred; as time went by, the significance gradually lessened. When possible the communal fire was placed in front of a rock shelter or cave; in a place safe and convenient for the use of everyone. The necessity for a screen to protect the early bonfires from the wind may have been the reason for the round form of house thought to be the earliest.
Later, individual fires were built in the center of the family shelters, where the hearth became known as the chimney. The term was then used to include the hole or flue that carried off the smoke of the fire burning in a pit in the center of the floor. History has failed to record the inventor, or to state the place where chimneys as we might recognize them were first used, but they seem to have been common in Venice before the middle of the 14th century, for a number of them were destroyed by an earthquake in 1347.
The principles of the chimney were poorly understood for many years. No matter how perfect they seemed, builders were never sure they would function efficiently. The first recorded effort to study the matter of smoky chimneys on a scientific basis was that of Louis Savot, a French physician, during the 16th century. He failed to find the real trouble, but he improved the form of the fireplace opening by narrowing the width, so that less air could enter on each side of the fire. He also showed that the flue should be smooth to lessen the friction of the ascending smoke.
The four elements are indeed the essence of life. All animals, plants, non-living objects, and energies are combinations of these elements as, of course, are we. Everything has its own unique blend of the four elements in it: everything that has substance has Earth in it; everything that flows and/or has feelings has Water in it; everything that involves sound, thinking, or communication has Air in it; and everything that has energy has Fire in it.
References
geology.about.com
lifeslittlemysteries.com
rsc.org
teachertech.rice.edu
csep10.phys.utk.edu
hearth.com