The aether is the bright air above the clouds. According to the Greeks, this element filled the universe outside our tiny central sphere. Air, though transparent to humankind, was thick, dull, and dim compared to the bright aether that encircled and surpassed our atmosphere.

Aether was the substance that the Greek gods breathed, as all mortals breathe air, and it was also the pure element of which the gods were made, as fire was the essence of the salamanders, air the essence of the sylphs, water of the undines, and earth the essence of the gnomes.

Aristotle thought that aether was the matrix of the universe. For him, therefore, aether was the unchanging element out of which the variable four elements arose. Hence aether was not hot or cold, moist or dry. The original unified material of the universe, it comprised, in its unity, all the variety of the four elements.

To Aristotle aether was a shining substance of utter purity, the quintessence. To early physicists, however, it was the medium through which light traveled. It explained how light was able to travel, because without it, there was no field for light to act upon.

Aether was considered to be present everywhere, within every substance and filling every space. To the first physicists, the properties of aether gave rise to manifestations like magnetism, gravity, and electricity. Aether as a medium fell out of favor in physics though, as the discipline discovered that light could travel without a path and act at a distance without a connection.

The God Aether

Aether personified, deified, was light. According to Hesiod, he was the son of Erebus and Nyx, the goddess of night. Erebus was, in a sense, the god of darkness, or of the dark air that surrounded the realms out of our sight, where the dead lived. Hyginus described him as the offspring of Chaos and Caligo.

Aether was thus one of the primordial gods, before the Titans. Hyginus also said Aether was the father of Earth, Sky, and Sea, from his mating with his sister goddess Hemera, the Day.

Aristophanes said Aether was the father of the Nephelai (though he also called them the daughters of Ocean), who fetch the rain in pitchers of cloud. Rain is certainly born out of the thickening air. Other authorities, however, say the shape-shifting Nephelai were daughters of the watery Ocean.

Aether had children who were daimones, spirit phantoms, as well. From the union of earth and upper air came a number of spirits of pain and misery.

At evening, Nyx would draw her cloak between the upper domain of Aether, and the lower of mere Air, and bring mortals blessed rest. The great ethereal gods, however, lived in the light, except when they chose to visit dusty earth.

 Source: The best online source I’ve found for Greek myths is Theoi.com, and I used it here, though I certainly can’t blame it for my misunderstandings.