I was looking for random info on the web and stumbled on a big spoiler (to me) where it said that the great old ones perfected all sciences and such.

Now I am nearing the end of The Waste Lands (book 3), where they discovered Lud and all the machines such as Blaine the Mono, the airplane, etc. I was really curious as to where all these machines came from and this spoiler really ruined it for me.

I just want to know when this fact is revealed. In which book? Please don't soil it any more Just which book this was revealed