Mithraic mysteries in the context of "Baths of Diocletian"

Sol is the personification of the Sun and a god in ancient Roman religion. It was long thought that Rome actually had two different, consecutive sun gods: The first, Sol Indiges (Latin: the deified sun), was thought to have been unimportant, disappearing altogether at an early period. Only in the late Roman Empire, scholars argued, did the solar cult re-appear with the arrival in Rome of the Syrian Sol Invictus (Latin: the unconquered sun), perhaps under the influence of the Mithraic mysteries. Publications from the mid-1990s have challenged the notion of two different sun gods in Rome, pointing to the abundant evidence for the continuity of the cult of Sol, and the lack of any clear differentiation – either in name or depiction – between the "early" and "late" Roman sun god.

Mithra (Avestan: 𐬨𐬌𐬚𐬭𐬀 Miθra; Old Persian: 𐎷𐎰𐎼 Miθraʰ‍) is an ancient Iranian deity (yazata) of covenants, light, oaths, justice, the Sun, contracts, and friendship. In addition to being the divinity of contracts, Mithra is also a judicial figure, an all-seeing protector of Truth (Asha), and the guardian of cattle, the harvest, and the Waters.

The Romans attributed their Mithraic mysteries to Zoroastrian Persian sources relating to Mithra. Since the early 1970s, the dominant scholarship has noted dissimilarities between the Persian and Roman traditions, making it, at most, the result of Roman perceptions of Zoroastrian ideas.