From the book "Gods About Us", Max Rempel
The simplest and most intelligible nomenclature for the earthly and the higher levels-spheres uses the term density. The implication is that earthly matter is denser than heavenly matter, and the farther one climbs into the heavenly spheres, the lower the density and the higher the frequency of vibration of the divine ether. This is a simplified and earthbound description, since it is difficult to describe that which does not and cannot exist in our material world.
1. The first, the densest density, is simple matter. For example, simple stones, simple water, simple air belong to the first density. (I say not matter, but specifically "simple matter," because our planet, the oceans, and the atmosphere are not nearly as simple as they seem, and they too have a soul and are no less multidimensional than we are, that is, they exist not only in the first density.) That is precisely why we define the first density as simple, dead matter.
2. The second density is simple life. Simple bacteria, simple plants, simple animals. Again, our biosphere is not as simple as it seems, but nevertheless simple, disconnected animals and plants symbolize the vibration of the second density.
3. The third density corresponds to the simple human being, who has risen above the animals in his awareness of the world, who is already moved by feelings more complex than the primitive animal instincts.
This is the humanity of the past. And, to some degree, of the present.