Lenses

Two special lenses, one an ancient convex purple lens of Gargish origin and the other a blue concave lens of Human design, these two items allow viewing of the Codex of Ultimate Wisdom from the Ethereal Void.

Age of Enlightenment
The convex lens was initially crafted by the gargoyles Naxatilor and Lor-wis-lem many centuries before the events of Ultima V in order to view the Codex. At this time, the Codex lay deep within the Realm of the Gargoyles, available to winged Gargoyle in possession of the glass. With the removal of the Codex by the Great Council, the Gargoyles were no longer able to view their sacred text, and ultimately the lens was broken by unknown means and the remains placed within the Hall of Knowledge.

With the assistance of the Gargoyle Lensmaker, the Avatar was able to mend the ancient red lens, and was then tasked with the creation of a human counterpart, a concave blue lens. Ephemerides of Moonglow proved himself capable of the creation of such a lens, requiring a glass sword to be melted down in order to produce such a magical piece of glasswork.

Placed between the flames of Singularity and Infinity, the Avatar returned the Codex of Ultimate Wisdom to the Ethereal Void with the assistance of the Vortex Cube and the eight moonstones. With the restoration of the Codex, peace prevailed between the two people. Both lenses were now required to view the Codex, with Lord British in possession of the blue lens, and Lord Draxinusom the red.

Age of Armageddon
During the 200 years that passed before the Avatar next returned to Britannia, the lenses had somehow found their way to the Royal Museum, with the kings of the two people seemingly no longer in need of the wisdom of the Codex. It was at this time that the Isle of Fire, the former abode of the dreaded Exodus arose from the seas. The Avatar discovered that the lenses possessed the power to move objects to and from the Ethereal Void. Using this power, the Dark Core of Exodus and the Talisman of Infinity were banished from Britannia, preventing the return of the hellspawn.

In Ultima IX, the red lens had come into possession of the new lord of the Gargoyles, Vasagralem. Despite his anger at the destruction of his people in their underseas home of Ambrosia, the king would give the Avatar the lens in exchange for a gargoyle queen egg, which would allow the reestablishment of is people without the Pride which had destroyed them. The blue lens had mysteriously come under possession of the gypsy Rom Baro of Minoc, who after realizing the dangers Britannia faced if he did not cooperate with the Avatar, allowed the hero access to his wagon. Doing so brought down the wrath of Blackthorn's curse, causing the gypsy to burst into flame. In possession of these two lenses, the Avatar was able to decypher the Codex one final time and gain the knowledge required to defeat the Guardian.

Trivia

 * In Ultima VI the Avatar is instructed to place the Concave and Convex Lenses midway between the Codex and the two Eternal Flames. This was meant to focus the light of the flames upon the Codex. With real world physics, however, placing the two different lenses halfway between the lightsource and the object would not have worked as the game intended.
 * The function of the lenses in Ultima IX is different, and the lenses are much smaller, less round, and the Gargoyle lens is red.