The idea for the Probability Trance as described comes (in part at least) from Daniel Dennet's Multiple Drafts Model of consciousness, where 'conscious experience' is the artifact of competition between multiple neuro-subprocessors. The Dunyain, the idea is, have developed the ability to direct and access those subprocessors - or 'Legion' as they call them - through the Probablity Trance.
Thank you Curethan! I have been hoping for some insight in 'legion' for ages!
@ Swense - love the idea that sorcery is persuasion--persuasion that the world should be other than the way god made it?