The Codex of Ultimate Wisdom is a magical book, bound in leather and gold, that incorporates all knowledge that exists. It is said it holds the "one right and true answer to any question." When a reader approaches the book it is always open to the page they seek, and they are always able to read it despite their language. Emblazoned on the cover is the symbol of the Codex, a set of six lines and two circles arranged to touch three central circles in different manners. This symbol represents the eight Virtues and three core principles of Britannian and Gargish virtue, which the Codex inspired.
The following message is revealed by the Codex as a result of the quest ordained by the Shrine of Singularity:
"To return the Codex to the Vortex, place a convex lens exactly midway between the Codex and the Flame of Singularity, so that the light from the flame converges on the Codex. Place a concave lens between the Codex and the Flame of Infinity, so that its light diverges over the Codex. Then place the eight Moonstones within the Vortex Cube. Set it on the ground in front of the Codex, and use it to return the Codex from whence it came."
In the documentation that comes with Ultima VI, the following is revealed by Lord British as a prophecy given by the Codex:
"One will arise with the strength of an army, the vision of a prophet and the heart of a saint. This Great One will bring about an end to the struggle between the Darkness and the Light."