"Letters of Abelard and Heloise" by Peter Abelard and Héloïse is a collection of correspondences written in Latin during the 12th century. These passionate and intellectual letters document the relationship between a prominent theologian and his gifted pupil following their ill-fated love affair and retreat into monastic life. The correspondence offers intimate glimpses into medieval gender roles, love, and religious life while serving as a cornerstone of Western epistolary literature. Their authenticity has been debated by scholars for centuries.
Wikipedia page about this book: en.wikipedia.org/wiki/Letters_of_Abelard_and_Heloise