Hillman’s slim volume is the best book I have read about the significance and experiential weight of dreams. He opposes the therapeutic and vulgar divinatory approaches that want to merely convert dreams into utilities of waking consciousness. While situating his study within the psychoanalytic tradition, he constructs his theory with extensive reference to classical notions of death and the underworld.
Magicians reading carefully can also find a wealth of pointers about the “astral” and the full range of visionary experiences which access materials from an unconscious source–collective or individual. In fact, this book is one of the most valuable texts I have found for that purpose.
An early monograph by Hillman, The Dream and the Underworld has a style that is more incisive and demanding than his later popular work like The Soul’s Code. He often uses untranslated Greek terms in order to orient the reader to what is likely to be at first an alien perspective on the underworld into which we all must descend. Although short, it requires genuine work to read, and it should repay the effort well.