MITHRAIC STUDY AND LEARNING
Ancient Mithraism was a path of specialized knowledge that progressed over a period of years. Candidates for the various Mithraic Grades were required to learn the secret teachings of each grade, and then undergo an initiation ceremony to both confirm that learning and to make it a part of the very being of the candidate.
The modern solitary Mithraist is at a distinct disadvantage in not being able to learn from experienced Mithraists, and to not have direct feedback to make sense of the teachings given. Today Mithraic knowledge for the most part consists of scholarly, non-religious texts. Such volumes go through the physical remains of Mithraism in great detail, with the intent of at least unlocking some of the underlying cosmology... but they do not touch in any extent on the teachings of the Mysteries themselves.
The best one can do today is to study Mithraism and and any and all related materials, and work to make sense of the various paths of knowledge. Such learning is in no way a replacement for the actual Mysteries, but it is the most honorable course of action at this time.
Continuing to study everything related to Mithraism while you practice personal rites is more than a way to increase your knowledge. It is also one of the most important means of staying involved with Mithraism as a religion, and of keeping yourself progressing as a person.
The "online bookstore" of this website lists the basic Mithraic and Zoroastrian materials that are in print as of this writing. However, those materials, as valuable as they are, are only the tip of the iceberg. There is more Mithraic information out there, and there are other paths which can help shed light on Mithraism as a path of the Mysteries.
Tips for further study:
I. Once you have the books that are in print, the next step is to look for the materials that are out of print. This can be difficult, but is always highly rewarding. The easiest way to find out of print Mithraic materials is to visit the library of a large university. Many out of print Mithraic works will be in the stacks, others will be in the computer book catalog and may be ordered from other libraries. There is also a vast treasure-trove of Mithraic materials in scholarly periodical journals, such as "The Journal of Roman Studies." Those can be found in the periodicals section of larger university libraries.
II. Astrology - a key to Mithraic symbolism. There is much that is astrological within Mithraism. The Planetary Deities and the Mithraic Grades are perhaps the most powerful examples, but there are other astrological and cosmological elements in Mithraism as well. Books on astrology can be very helpful in learning about the basic powers that are expressed through Mithraic symbolism. Books on ancient Greco-Roman astrology are particularly helpful.
III. Ceremonial Magic - a modern expression of the ancient Mysteries. While the Mithraic Mysteries were not exactly ceremonial magic themselves, they were certainly part of the religious/spiritual path that gave birth to ceremonial magic as it is known today. Organized rites to specific powers, using ritual tools and secret imagery are common to both. It has also been noticed that the Caballistic Tree of Life has definite similarities to the Mithraic Grades, as both show an interplay between the ancient Seven Planets and their powers.
IV. Fraternal Orders - organizational successors of the Mysteries. It cannot be proven that ancient Mithraism (or remnants of it) became fraternal orders such as Freemasonry and the Rosicrucians. However, the fraternal orders of today are certainly distant cousins of the ancient Mysteries, if not their direct children. Many organizational tips can be found in such modern groups. Joining one can be helpful, as can reading about them.
No matter how you approach your study of Mithraism, Never stop learning, and never assume you know "the" answers. Even the initiates of the ancient Mysteries could find successive levels of meaning within their paths. One could never learn all their was to know, for the closer a path comes to deity the more there is to learn. Keep studying, keep progressing, and keep an open mind.