Esoteric knowledge (of the chosen few) has always been embedded in our religions, literature and folklore. The early mythologies of the Greece, which were later upheld by the Romans, were very esoteric. In one of the mythological stories, Zeus releases three Cyclopses from the dark pit of Tartarus. Upon the Cyclopses release they gave Zeus his thunderbolt and Poseidon his trident. The Gods used their new gifts to defeat their enemy, the Titan giants.
You would think that there was such a thing as a Cyclopse at one time, with all the stories of them out there. Well, in a way there was. A Cyclopse had the capability's of a seer, using their "middle eye" or what we would call the third eye. Today, Hindu women wear this representation of a center eye as a dot. Once these Cyclopses left the dark pit (their lack of knowledge) they were able to give "gifts" by the strength of their knowledge. Alchemy isn't about turning basic metals into gold, as the uninitiated would have you believe. Alchemy is a process that shows a person their gold (enlightenment.) The phrase, "Testing Ones Metal" is straight out of Alchemy.
King Arthur had twelve "Knights of the Roundtable." This is a representation of our twelve astrological signs. Each sign having strengths and weaknesses etc.. King Arthur's sword, the Excalibur, was originally called the Caladfwich, which is Welsh for "Hard Lightning."
Lightning was the gift the Cyclopses gave Zeus to use against the Titans. This was considered the ultimate weapon of the Gods. Even the Celtic's had the cosmic Lightning Wheel (long story.)
Another Medieval phrase, "Slay the Dragon," came about by the brutality of the Inquisition of The Church. It would have been considered heresy for anyone to pursue what we would call enlightenment during the Middle Ages. If you had somewhat of a formal education, you could find the knowledge of the ancient sages through Alchemy and ancient esoteric writings from Plato, Homer etc.. Most men that wanted this ancient knowledge would leave their villages to search for one of the regions wise men, living in the forest or local cave. These men would tell the children that they had to go, "Slay the Dragon." After spending a sufficient amount of time with the old sage of the region, the men would return home to tell of their conquest and how they "Ate the heart of the dragon" (gaining all his knowledge.)
The Ancient Wisdom Masters hid knowledge within their individual particular expertise. Be it art, literature, mathmatics, science, arcitecture, religions or just mythologies and folklore stories for the common people of the world to find and improve their metal.