The idea of 4 elements are usually seen as obsolete metaphysics,
that finally collapsed centuries ago. However, this is only partly true.
The original theory made physical sense, but created nonsense when applied chemically.
Above Fire was supposed to exist a mysterious substance phlogiston,
with a negative weight to make the equations work.
(And you thought modern physics were weird?).
However, the idea of 4 elements still makes sense,
as the four physical states of matter:
solid, fluid, gas, plasma.
If understood as principal levels,
then Elements are still valid today:
: Solid, stabil, unmoving matter.
If the aspect of a fixed form is lost, then we'll get the next element:
: Fluid form, but the volume is still constant.
If a fixed volume also is lost, we'll get the next element:
: Fluid form and volume,
but still some substance that creates atmospheric pressure.
Air may be in perpetual motion, but it is always there.
Loose that and we'll have the next element:
: Nothing is no longer fixed, not even existence. Fire comes and goes.
But though it seems insubstantial, it still leaves tangible traces in the rest of the world.
If another aspect is lost, we'll have the next element above Fire.
Any suggestions? My own kandidate could be light, as it leaves no traces at all.
How about an element below Earth? Which aspect should then be added?
I wonder if Black Holes could fit, but there could be other candidates:
Any idea..?