Yes, Rudolf Steiner was both amazing but also bonkers. His books are super flowery and like Carl Jung, are a lifetime of study in themselves while also potentially being a cure for insomnia. Yet, he was truly an esoteric Jedi.
Knowledge of Higher Worlds is one of his more known books describing his own experiences with what he calls, many many many times in the text, the “Supersensable” worlds. What those are is a longer story but we can think of them as the inner worlds of his meditations.
This particular text has a very profound chapter (10 to be exact) which is especially important for sharing some secret keys to the nature of reality. That is all that is to be revealed for now regarding.
http://www.mediafire.com/file/pbzc4ebst9ao02r/KnowledgeOfHigherWorlds-RudolfSteiner.mp3 https://www.mediafire.com/file/oahax5gsuk9pxbe/KnowledgeOfHigherWorlds-RudolfSteiner.pdf