Melchizedek and the Mystery of Fire: A Treatise in Three Parts (1926) is a short work by mystic and occultist Manly P. Hall. It explores the symbolism of ancient rituals in Christianity, and their sources in earlier religions and cultural traditions. It also explains the human body's "occult anatomy," giving meaning and symbolism to our very organs and glands.

Canadian-born Manly P. Hall (1901-1990) was a writer and lecturer of mysticism for over 70 years. Introduced to the mysteries of the ancient world upon moving to Los Angeles in 1919, he quickly became a preacher at the Church of the People. At just 18 years old, he spoke about Pythagoras and Plato, along with newer doctrines like Theosophy and Rosicrucianism. 

Soon, this intense young man had caught the attention of the wealthy Carolyn Lloyd and her daughter, Estelle. The Lloyds became his patrons, funding an expedition around the world that gave Hall insight into ancient religions and traditions across the globe. He collected an extensive library of rare books of philosophy which he brought back with him to Los Angeles.

Over a seven-decade career, Hall embarked on an ambitious career of writing and lectures, giving thousands of talks throughout his life including two at Carnegie Hall. He wrote 150 books and pamphlets, plus countless essays. One of his earlier works is Melchizedek and the Mystery of Fire. 

Melchizedek is a Biblical figure who first appears in Genesis 14:18-20. He was a priest-king who offered bread and wine to Abraham after returning from battle. This is often considered a precursor to the eucharist in the New Testament.  

The book does not focus on Melchizedek, but uses him as a starting point to explore the mysteries of ancient symbols and how they have been incorporated into modern religion-specifically Christianity. Hall believed that the stories of the Bible were allegorical and that there were secrets hidden within the parables. In his view, today's Christians and Biblical scholars, while well-intentioned, are unable to look beyond the traditions they have inherited to the truth within.

Despite its short length, Melchizedek is packed full of information on mysticism. Incorporating ritual and legend from great ancient civilizations as varied as India, China, Mexico, and Japan, Hall demonstrates that the truth of humanity is rooted in similar stories across these cultures, and has continued into Biblical allegory. 

The final part of the work explores the human body, detailing the nerve centers, internal organs, spinal column, and glands. Hall associates different parts of the body with signs of the zodiac, and with places and events from the Bible and other spiritual stories. He felt that each human was a universe to himself, a living temple with its own High Priest.

Hall continued to grow in popularity and prominence throughout the 1920s and 1930s. In the early 1930s, he founded the Philosophical Research Society, creating a home for metaphysical thought and education, and for his extensive library. While some of the books were unfortunately auctioned off after his death, over 25,000 remain. The center is still in operation today.