In a letter addressed to Lord Charles (Charlemagne), Dungal responds to inquiries regarding the double eclipse of the sun that occurred in 810. He acknowledges the interest of philosophers and physicists in explaining celestial phenomena, citing sources such as Macrobius Ambrosius and Cicero. Dungal outlines the structure of the cosmos, including the nine celestial circles, and explains the motion of the sun, moon, and wandering stars within these spheres. He emphasizes the importance of understanding the natural order of the heavens while humbly admitting his limitations in knowledge.