Plato's student Aristotle (384-322 BCE) developed a different explanation for the elements based on pairs of qualities. The four elements were arranged concentrically around the center of the universe to form the sublunary sphere. According to Aristotle, air is both hot and wet, and occupies a place between fire and water among the elemental spheres. Aristotle definitively separated air from aether. For him, aether was an unchanging, almost divine substance that was found only in the heavens, where it formed celestial spheres.

We have selected vivid light blue and shimmering grey enamel to represent the nature of this element, and the two colours mix fluidly over the crisp guilloche engraving of the barrel. The matching cap motif is accented in the same vivid blue enamel as the barrel.