It's elementary...
The idea of 4 elements is usually seen as obsolete metaphysics, primitive theories that finally collapsed centuries ago.
However, this is only partly true. The original theory made simple physical sense, but created nonsense when applied in a more modern chemical context.
Above Fire was supposed to exist a mysterious substance phlogiston,
with a negative weightM otherwise the equations wouldn't work. (And you thought modern physics were weird..?)
However, the idea of 4 elements still makes sense,
if we regard them as the four physical states of matter:
solid, fluid, gas, plasma.
If understood as principal levels, then Elements are still valid today. It also corresponds directly to how we sense the world...
More than four..?
4 levels of existence only reflects the traditional, classic system. Why not imagine more? Therefore I've included the 5'th, while hoping for the 6'th...
E A R T H
Earth represents matter in its most solid, stabil, unmoving level.
Minus fixed form, we'll get second element: floating, fluid and flexivle, welcome to water...
W A T E R
Water represents the fluid and ever flexible form, volume constant. To paraphrase Ein(ander)stein: A liter is a liter is a liter, no matter (re)shape.
But if a fixed volume is lost,
we'll get the next element: air...
A I R
Fluid form and variable volume, yet substance enough to create atmospheric pressure. Otherwise winds (or ballons) could not exist.
Although invisible, storms throw trees, cows and humans around, dumping it miles away in a wasted landscape. Invisible by it self, but results are not.
In perpetual motion, yet always somewhere specific.
A variable vibrating vortex, location fluctuates.Yet in constant existence. Loose that, and we'll have the fourth element: floating, furious fire...
F I R E
Nothing is fixed, not even existence. Fire comes and goes. As a visitor that eventually has to leave.
But though insubstantial, it still leaves tangible traces in the rest of the world, by burning. We cannot touch fire, but fire can touch us. With no traces we'll get..?
L I G H T
If I should suggest a possible fifth element, it would be light. Light transcends every previously mentioned aspect; leaves no trace at all, and moves faster than anything.
Light is originally created within stars, large or small, therefore eternal. Forever wandering, their path illuminating the universe, to it self.
Light is only visible as colour. Loose all hues and we loose all sensual clues. Yet indirectly we still sense, in a sense this world: as equations, fields, patterns, structures, pure energy...
E N E R G Y
A six'th element boggles the mind, but then again: imagination is the only thing faster than light...
How does one visualize something if it has no visible aspects at all? If you should have a suggestion, let me know...