Some excellent explanation of Jung's ideas

Illustration painted by Jung in his Red Book
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I spent some time scouring the internet for tidbits about the Red Book and suddenly ran across this amazing page: The Red Book: Some Notes for the Beginner

Here's a blurb by way of explanation of what the Red Book is for those who don't know:

“The years. . . when I pursued the inner images, were the most important time of my life. Everything else is to be derived from this. It began at that time, and the later details hardly matter anymore. My entire life consisted in elaborating what had burst forth from the unconscious and flooded me like an enigmatic stream and threatened to break me. That was the stuff and material for more than only one life. Everything later was merely the outer classification, the scientific elaboration, and the integration into life. But the numinous beginning, which contained everything, was then.” —c. g. jung​

During World War I, C. G. Jung embarked on an extended self-exploration he called his “confrontation with the unconscious.” At the heart of this exploration was The Red Book, a large, illuminated volume he created between 1914 and 1930, containing the nucleus of his later works. It was here that he developed his principle theories of the archetypes, the collective unconscious, and the process of individuation that would transform psychotherapy from a practice concerned with the treatment of the sick into a means for the higher development of the personality.

While Jung considered The Red Book to be his most important work, only a handful of people have ever seen it. It is possibly the most influential unpublished work in the history of psychology. Now, in a complete facsimile and translation, edited and introduced by Dr. Sonu Shamdasani, it is available to scholars and the general public. It is an astonishing volume of calligraphy and art suggesting influences as diverse as Persia and the Mayan empires—a work of beauty on a par with such illuminated manuscripts as The Book of Kells and those of William Blake. This publication of The Red Book is a watershed that will inaugurate a new era in Jung studies.​

I read the Red Book a few years ago. It's tough going. I definitely don't recommend it as a first entry into Jung's writing! The link I posted at the top of the page does an amazing job of explaining what's going on in this very challenging book. In fact, I learned quite a bit from reading it. Many parts of it were mystifying to me until discovering this key to understanding it.