The book has one chapter that presents the following interesting theory: maybe aliens are not from other planets, but from other dimensions.
Yes, this is what I think. John Keel is a good read on this subject. Synonmous with "alien" is the small grey. I consider an interdimensional entity, capable of mimicking human technology(including the flying saucer !.)
I believe Germany was developing the flying saucer - a terresterial vehicle capable of great speed during WWII. I believe the USA aquired this technology along with rocket scientists. I believe the trade off was that Third Reich leaders like Hitler and Bormann were granted asylum in South America.
My mother-in-law is an one dimensional entity that has only thickness.