Four elements and the problem with the the fifth element. There are many fundamental concepts in kabalah which come from Ancient Greek Science. I wrote a whole essay about this once long ago [That essay called Ten Sepherot in some blog entry]. The "Aether" was one of the first times I noted this. So what my learning partner suggested was the Greeks got it from the Kabalah. But then that just makes it worse. Since it is wrong, then it was the Kabalah that mislead the Greeks.

Aether is not the same thing as space. If someone had suggested that empty space is a thing in itself with nothing in it, then that would have been an insight. But that is never what anyone is referring to when they talk about the four elements and then the fifth one.

I went into some detail about this in terms of the ten sepherot and the ten orbits of the planets and sun around the earth from Ptolemy and Medieval science. But I brought a lot of other things along teh same vein but with less detail.  Still the point is the same.