A mantra is a word meant for meditation at the shrines of Britannia. It is chanted repeatedly during the meditation, first one time, then two times and finally three times. Using the correct mantra, the shrine will give the traveler insight to the virtue it stands for.
Each of the Eight Virtues has its own mantra:
The mantras were first encountered in Ultima IV, where each meditation cycle would net a different message. After that, the mantras of Britannia stayed the same, although it was still possible to solve quests to get the words again. In Ultima VI, the gargoyle mantras appeared as well.