Manly P. Hall 
Melchizedek and the Mystery of Fire [EPUB ebook] 

Originally published in 1926, this short book focused on the symbolism surrounding the ancient patriarch Melchizedek serves as a concise introduction to important imperceptible truths."The elaborate rituals of the ancient Mysteries and the simpler ceremonials of modern religious institutions had a common purpose. Both were designed to preserve, by means of symbolic dramas and processionals, certain secret and holy processes, by the understanding of which man may more intelligently work out his salvation. The pages which follow will be devoted to an interpretation of some of these allegories according to the doctrine of the ancient seers and sages."