This is perhaps the most interesting presentation of the theory behind the Giza pyramid I have ever heard. Chris gives this lecture some time after his first book, the Giza Power Plant and his second one on the Lost Egyptian Technology. I am paraphrasing but he says the technology of the people who built the pyramids was based on acoustics, and non-linear acoustics. For instance - the brain resonates at 6 hertz, and the pyramid's is between 6 and 9 hertz. But why is this important? It has to do with unifying the left brain, the right brain, and bringing a state of harmony. If you start around 7 minutes he discusses what the civilization was like and what they were achieving with this mastery of acoustic technology.