The Pillars of Nosgoth pose an interesting problem: they are fundamental to the underlying narrative of the series and yet the games provide contradictory information about their function and purpose.
Here, I will speculate and provide you with my solution to this riddle.
The Pillars Were Mortal, Once
This is probably the most controversial idea — and that’s the reason I’m leading with it. I think the Pillars were once either powerful wizards belonging to the winged race, or an allied race of creatures, however the former is more likely.
Whuh-why? Because their principles are engineered, artificial.
On Earth, there are no “mountains of mountain-ness,” “lakes of water-ness,” or “caverns of cave-i-ness.” There are no “fires of perfect burning.”
This makes it clear at least, that the Pillars aren’t a natural formation, but why “formerly mortal?” Because monuments do not serve a purpose, they do not make decisions, and they do not require a caretaker to be a monument.
This might sound absurd but a monument is a monument. The Pillars might be magnificent and magical, they defy natural law, but they’re quasi-sentient.
A monument is designed to “stand the test of time,” and they do this with varying degrees of success. Look at pyramids around the world. Sure, the Pillars are magical but the magic part is apparent — they reach forever into the sky.
No, there’s something else at work.
The Altar of The World
The nature of Sacrifice is a recurring theme throughout the series. Kain ritually slaughters the members of the Circle to purge the Corruption, and ultimately refuses to kill himself to complete the cleansing.
Sacrifice is often memorialized in stone — it’s so ingrained in the Final Fantasy series that we scarcely blink an eye when a rock grants us magic powers.
Magicite (FF6) is the remains of former Espers.
Materia (FF7) is formed from hardened Lifestream.
The Fayth (FFX) are hardened or crystallized mortals.
L’Cie (FF13) become crystal upon completing their Focus.
*Palom and Porom (FF4) become stone to protect the party.
*The Warring Triad (FF6) become stone to end their civil war.
*Seymour’s mother (FFX) becomes Anima to protect her son.
*Fang and Vanille (FF13) become crystal to save the world.
Magic comes from rocks and rocks come from people, especially people who sacrificed themselves or were sacrificed to protect others.
All the above examples come from the same publisher and the same series, but there are five examples — whether it’s a person, a person’s spirit, a memory of the person, or other supernatural forces at work, sacrifice has a form.
And that form is stone. (Or crystal. Whatever.)
Called to Protect and Serve
If the Pillars are formerly mortal, transformed upon their deaths (or sacrifice) then it follows that they require Guardians after a fashion — not just to bestow powers upon, but also as companions, to keep the Pillars “sane.”
The Pillars choose their Guardians, no one volunteers to serve them.
Spirits which are neglected or forgotten become willful and destructive — I’d provide an example, but it’s the premise of a majority of ghost stories. The concept is similar for people (and also vengeful deities) who are forgotten — importantly too, for sacrifices which go unobserved.
The winged race represents memory of the Pillars’ sacrifice. As they die out, there is no one left to remember. This plays a role in the Pillars’ collapse.
Memory is an important theme in the series. Ariel claims to remember what others have forgotten in Soul Reaver, and murals, monuments, and memorials feature prominently in each game (except Blood Omen 2, I believe).
This is just the first part of my hypothesis about the nature of the Pillars, their role and function, what happens to them, and why.