Truth

Truth is one of the three principles.

Truth is the foundation for the virtues of Honesty, Justice, Honor and Spirituality. The symbol of Truth is the Book of Truth, which can be found in the Lycaeum; the Fortress of Truth on Verity Isle.

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.

Truth on Serpent Isle
The mages of Moonshade took the principle of Truth, despite acting in its name, not very serious. This might also 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 for this mockery of the Truth is, when the Avatar is brought before a court by the Mage Lord.

The real name for what these mages follow is Illusion.