That is all Greek, but Avatar is set in an Asian-inspired universe. And they do cover one other element "metal" rather lightly, but it's part of Earth which is not accurate if we're going by Chinese belief.
And for that matter, where is Wood?
Wood feeds fire;
Fire creates earth (ash);
Earth bears metal;
Metal collects water;
Water nourishes wood.
Wood parts earth;
Earth absorbs water;
Water quenches fire;
Fire melts metal;
Metal chops wood.
So why was Wood ignored in the creation of the Avatar universe? And why did they include Aether which was a Greek ideal into the universe.
I suppose the Spirit World could represent the Tibetan belief of "Space" or the Japanese belief of Quintessence...but if that's the case why is there only the Spirit World and spirits who bend this Quintessence?
Why aren't their humans who control the intangible "magic" of Aether? Is it supposed to be that it's too elusive for mortals to comprehend? Your thoughts?