Heavenly bodies are made from a special incorruptible substance called aether or quintessence, rather than the matter found on Earth.

Aether was more than a mysterious extra material. It solved a structural problem in Aristotelian physics.

Earthly matter was built from earth, water, air, and fire. Those elements had natural places, could transform into one another, and belonged to a world of generation and decay. But the heavens seemed to move endlessly in perfect circles without wearing out. Aristotle therefore assigned them a different kind of matter: aether, whose natural motion was eternal circular motion.

The result was a two-material universe. Rocks, oceans, flames, and bodies were one kind of nature; stars and planets were another.

The distinction weakened as early-modern astronomy increasingly treated celestial objects as physical bodies rather than a separate ontological class. Newton’s mechanics was especially important because one gravitational framework could describe a falling body on Earth and the Moon’s orbit. In the nineteenth century, spectroscopy supplied a direct chemical test: stellar spectra reveal familiar elements such as hydrogen, helium, sodium, calcium, and iron.

There is no single clean date when “aether” ceased being accepted, so this card should not be used for precise lifespan statistics. What changed was a centuries-long collapse of the idea that celestial matter belongs to a fundamentally separate category.