Peter Abelard is considered to be the founder of the University of Paris. He studied under the nominalist Roscelin de Compiegne and the realist William of Champeaux. Disagreement with William led Abelard to withdraw to the provinces and set up his own school at Melun, in northern France, in 1104. He returned to Paris in 1116 to teach. A disastrous love affair with the brilliant and sensitive Heloise followed in 1118. Abelard had been hired as her tutor, and, after the birth of their son, they were secretly married. They later separated, and Abelard became a monk and Heloise a nun. Their correspondence during their years of separation is a literary classic. After the separation Abelard withdrew to Brittany and wrote The Theologia Summi Boni, which was condemned at Soissons in 1121. When he returned once more to Paris in 1136 to teach, his theology was condemned at Sens, chiefly because of the influence of Bernard of Clairvaux. Peter the Venerable of Cluny mediated the dispute between the two while Abelard was on his deathbed. Abelard spent his last days peacefully and was buried near Heloise.