I think that Galbatorix is able to control spirits to gain power and by continuing to gain more spirits they gain more power.

On page 640 on Eldest there's a line "The consciousness of the Rider felt strange to Eragon, as if it contained multitudes; scores of distinct voices whispered in the caverns of his mind, like imprisoned spirits begging for release."

any thoughts?

Good point but I dont know if galby is doing that. He might just be absorbing energy from other living things.

i agree galby might have used the isidar mithrim but remember it was smashed by arya when they tried to save eragon

but remember Galby has NEVER been to Farthen Dur so how could he have stored the energy. No They get thier power from souls some how.

There could be a lot of reasons... i like the idea about him controling spirits and souls though... it fits the best in my opinion

Yes but how do they get power from the spirt and souls, like a sorcer. Please share your opion.

maybe from taking down the riders in the fall? i remember also that in eldest it said that galby had some training from shades... maybe he learned something from them to gain his strength

Good Idea, and maybe he is useing spirts like Durza's to gain power (Durza was powerful and would ad alot of strength to him), or he is taking the spirts of those who died in the empire during his rule somehow.

I think maybe Galby has learned a spell that makes them more powerful and he is using it to make Thorn age faster. They could be getting their power from the VOS>

IF Galby knows of the VOS then what is the point of Eragon going there if he would be ambushed. The elves don't know exactly where it was or what it was (please correct me if I'm wrong). I don't think Galby is getting his power from VOS.

Or something like it. He could be getting his powers from some shade power he learned.

they could b gettin there power from evil dead souls, etc.... as it says Eragon tries to break into Murtagh's mind but finds it filled wiv voices....... could b the answer (i pickied this theory of some1 else, so it aint truely mine)

on Page 640 of Eldist, The consciousness of the Rider felt strange to Eragon, as if it contained multitudes; scores of distinct voices whispered in the caverns of his mind, like imprisoned spirits begging for release. I think this is talking about good spirts (evil spirts would love a chance to inflict pain) because they sound like they want to get out.

Like how you become a shade, is through evil spirits controlling you and they'd also love to inflict pain.

Yes but would a evil spirt want out if they had a chance to inflict pain? Pg 650 ...like imprisoned spirits begging for release.... Se that is the reason I think it is good spirt not evil.

I posted this in the eragon vs murtagh;

one possible reasons why murt. is so strong.
we were introduced to a new concept of absorbing life force from living beings, galb. has a massive army, who will question the loss of a thousand men or prisoners.
the life forces could be stored in gems.
this power could be used to accelerate thorns growth and increase murt. strength as well as his speed in healing thorn.
this could also be why galb. is getting stronger and more reckless’ in magic, after all he is not spending his own life source.