Ars Magica by Judith Tarr is a historical fantasy novel published in 1989, blending real history with magic, centered on the life of Gerbert of Aurillac (who became Pope Sylvester II) as he rises from a peasant monk to the papacy, using both intellect and forbidden magical arts. The book explores his journey through 10th-century Europe, focusing on his study of mathematics, astronomy, and magic, and the personal cost of wielding great power. It's known for its character-driven narrative and its integration of historical figures and events with magical elements, making it a popular read for fans of historical fantasy