Gnosis, in the hands of Roberts Avens, is a perennial philosophy of the heart. This book provides a readable, uncomplicated, and reliable introduction to Gnostic thought in the works of Martin Heidegger and James Hillman.
If someone ever asked me how something can be real that isn't a thing (i.e. a being), I'd give them this book. The ultimate unity isn't a thing, but a dance, a play.
I cannot speak to the author's understanding of Hillman, in which I have no expertise. However, his understanding of Heidegger is so flawed as to be at many points not simply a strange interpretation or variant notion but simply wrong. The equation of Dasein with the soul is bad but not disastrous. The equation of the animus mundi with Heidegger's "world" betrays so fundamental a misunderstanding if Heidegger's thought as to imperil anything that might be associated with it.
Ultimately, whatever insights are available here are more productively found by reading Corbin or Heidegger or (I presume) Hillman. I was disappointed especially because the title was so suggestive and provocative, and I believe that interesting things might be said here, but by attempting to link Heidegger too closely with depth psychology, Avens does violence, at the least, to Heidegger in a catastrophic way.
The introduction was exceptionally helpful the book is good, but best to have read a fair amount of Hillman and Heidegger first. Actually, I wish I had read Henri Corbin before now- but that was better handled for a beginner than the Heidegger. I didn't care for Avens constant use of internal quotations and would have preferred more paraphrasing to help the text hang together in a more cohesive voice.