I've always been interested in studies about collective consciousness. To me egregores are just mass thought forms that are created by momentums in our own individual consciousnesses. There's common societal ones like manners all the ways up to beliefs and fears and disease.
People who have the largest megaphones (the rich and the media) tend to have the ability to direct and sway the collective mind and inject thier own thoughts easily into it.
We ourselves are connected to the collective mind at all times. When we positively work on our selves and the purification of our own mind we lend some of that purity to our nation and by extension mankind.