Aether? Quintessence? The fundament of all things? What enables space, counterspace, and everything in between? {Hint: Walks like a field? -- Must be a field!}
Not a gas. He was right though to distrust the hard core "atomists." While the Aether clearly can't have mass, neither can "electrons." We assign them a mass, but just try to grab one and weigh it. Electrons, again by definition, are "probability clouds" not "particles." Clouds of potential with apparent mass only. Ethereal.
I see the Aether as a field. In other words, a matrix of polygons, their nodes connected in such a way as to allow for infinite expansion and compression. Geometry following the Golden Ratio is the only way to enable such infinite stretching and squashing. That same geometry being responsible for all QM observations. But I digress. Further, I see the Aether as having a preferred (or average, unperturbed) density because thinking so just makes me feel more comfortable, but I dunno. Seems logical to me, though perturbations of the Aether are probably as ubiquitous as the Aether itself.
Should everything finally be reduced to its lowest energy state we just might have to wait for the next Bang! Perhaps "order" increases in counterspace in direct proportion to disorder in space.