>>509767875 (OP)It's partly rooted in theosophy and the ideas of Helena Blavatsky. Basically, there's the belief that there were superhuman races in the past (Aryans, Hyperboreans, Atlanteans, ...) with spiritual powers, from whom all civilisation and wisdom ultimately derives. They were diluted due to interbreeding with lower forms of humans. By eugenic breeding of especially Nordic people, who have the highest genetic traces, a new masterrace could be created that might match those superhumans of the past.
I think that kind of belief system is a bit far removed from us today, with modern insights into the history of mankind. Even if you believe scientific truths are falsified, you still have to wonder how those ancient superior races managed to fuck themselves over by basically breeding with animals if they were so smart.
The nazis were right about this though: there were Aryans (i.e. Indo-Europeans), who were stronger and probably smarter than most people around them, and managed to set themselves up as the ruling elite over large swathes of western Eurasia. Then they built a lot of cool civilisations. They probably didn't have any psychic powers, however.