Mystery

From Srafopedia

The term Mystery derives from Latin mysterium, in this context meaning "secret rite or doctrine." An individual who followed such a 'Mystery' was a mystes "one who has been initiated," from myein "to close, shut," a reference to secrecy (closure of "the eyes and mouth") or that only initiated people were allowed to observe and participate in rituals.

The term is used in Eastern Christianity to refer to what the Western Church currently calls Sacraments. In the Early Church they were kept hidden from the pagans lest they become objects of ridicule. As the Age of Persecution ended, the secrecy was gradually relaxed. But the term continued to be used. Originally the term "Mystery" was used in both the East and the West, as shown from the "Mystagogical Homilies" of St. Cyril of Jerusalem and the work, "On the Mysteries" by St. Ambrose of Milan.

The old meaning of mystery is also preserved in the expression "mystery play". These stage performances of medieval Europe were known as such because the first groups to perform them were the craftsmen guilds, entry to which required an initiation and who zealously protected their trade secrets.

(Source: Wikipedia)