Guidestones are stones that, when held and activated, project holographic figures who are designed to act as guides and give information. The guidestones in the Celestine Library are specifically designed to help any newcomer with finding books. They have their own personalities and specialties. Some guides know more than others, some less.
The known, named guides at the Celestine Library are:
- Tibrus: A blue knight wearing a breastplate and a helm. Specializes in medicine, the arts, and the strategy of war.
- Bactrus: A bald man with a hook nose and thin eyebrows. Has pale skin and white clothes. Uses a cane. Seems to specialize in history. Tells Jason about how English came to Lyrian, as well as the Petruscan Scroll containing Darian's last living place.