The Celestial Incarnae are seven souls of the Games of Divinity.
When the Primordials made Creation, the Games invented conflict in all its forms, and it was so enamoured of this invention that it staged a great war between itself - played out by its agents - and its brethren, and in doing so, it filled itself with power, making the Incarnae mightier than any of the Primordials' demon children. The Celestials were the only beings infused with this power, which erased much of their memories - other souls of the Games, like Argenta, the Girl in the Silver Hat, retain their knowledge of their association with the Games (see Ikselam/MadTeaParty, but are less glorious.
The creation of the Exalted is that of the shattering of the defining souls of the Incarnae - it is the reason that they know not who they are. Alloyed with one other soul, they produce the identity of the Exalts as a whole, while the five remaining sould shape the division of Castes. The Maidens are in fact five projections of a single being, who created all the Sidereals and many other agents of Destiny besides. It is suspected that her Jupiter aspect has been experimenting on her shards, and has some inkling of her true identity.
This is really intreguing. I like it. Perhaps enough to incorporate it into my Sidereal game, which is already building up to dealing with the larger questions, like this. The big question is how... --Dissolvegirl
Upon further introspection, I have come to not like this theory.
At this point, I want the Incarnae to be qualitatively different than the Primordials... they are, to me, big elementals, while the Prims are big Celestial Gods, which is to say that the Incarnae are beings of substance rather than concept.
I still like the Five Maidens Are As One idea, and it makes them more interpretible as elemental beings of Destiny (which is demonstrably a substance, though one with very strange properties.) The Exalted unified under the banner of "little elementals" makes them more distinct from God-bloods too, which I like (though this means that Exalted should have quite strange children.) - willows
It's the "Five Maidens as one" idea that I like best about it all. I view primordials as big aliens, possibly from their own "world," whereas the Incarnae are more human and accessible. I also really like the idea of the GoD being a primordial, although the tea-party idea is a bit too.. anachronistic.. for my game. ;) --Dissolvegirl
I view the Incarnae as giant anthropomorphic machines, kind of like uber-Alchemicals. - Quendalon