The elements simply exist intrinsically in the setting - that's why you get the division of 6 elements in Eureka. Then, on top of this, you get the umbral and astral aspecting, which influence their intensity and nature. So ice would be an inherently existing thing in the game, and the mage can shape aether into this element. There isn't a great deal more to it. I also don't see much of a relevance, since spells are already divided along these lines.