Truth

Truth is one of the Three Principles of the Eight Virtues of Britannia.

Truth is the foundation for the virtues of Honesty, Justice, Honor and Spirituality. In the case of Honesty, Truth is the only principle leading to it.

The symbol of Truth is the Book of Truth, which is kept in Ultima IV and Ultima IX in the Lycaeum, the Fortress of Truth on Verity Isle. Many people from Britannia go to the Lycaeum to meditate or search for Truth.

The shrine of Truth with the corresponding test is situated on the Isle of Fire. It is basically a test to see through illusions and false leads. The shrine itself dissapeared before Ultima IV, when the Isle of Fire sank into the seas, so it wasn't used in the quest for the Avatar. However, the Avatar gained access to the shrine when the Isle of Fire reappeared during Ultima VII.

Truth on Serpent Isle
The mages of Moonshade took the principle of Truth not very seriously, despite acting in its name. This might be because of their heavy reliance on illusion and deceit as well as their general feeling of superiority because of their magic powers. A prime example of this is the process held when the Avatar is brought before their court by the Magelord. A more correct name for the principle these mages follow would be "Illusion".

The Mirror of Truth is the symbol of this principle on Serpent Isle.