Peter Abelard 
The Love Letters of Abelard and Heloise [EPUB ebook] 

Abelard, Professor of Logic and Canon of Notre Dame, the most celebrated man of his day, being thirty seven years of age and having so far lived the life intellectual and scorned the passions, meets Heloise, a beautiful and learned woman of nineteen, and falls desperately in love as only the late lover can. Reason and religion are thrown to the winds; he would marry her, but she loves with a devotion as mad as his, and marriage would arrest his advancement in the Church, so she refuses yet gives him all.