General Resources

The Medieval Sourcebook contains links to many medieval texts, theological, spiritual, literary and historical.

Early Latin Writers

Augustine

Sant’Augstino has the Latin Opera Omnia of Augustine and a collection of links to English translations of several.

Boethius

Boethius’s Consolation of Philosophy is available in a very nice Latin edition. An English translation of the Consolation and several theological treatises on the Trinity in Latin and English from Project Gutenburg.

Isidore of Seville

Wikisource has De Rerum Natura.

John Scottus Eriugena

Wikisource has a few links including one to book 5 of the Periphyseon.

Arabic Philosophers

Averroes

Averrois Opera Omnia  

High Middle Ages

Abelard

Wikisource has tons of Abelard texts in Latin.

Peter Lombard

The Fransiscan Archive has lots of material on Peter Lombard, including links to Lombard’s Sentences and commentaries on them by lots of other figures, like Francis of Marchia.

Albert the Great

Grosseteste

Grosseteste’s works are available online at https://www.grosseteste.com/

Thomas Aquinas

From Pasnau’s homepage there is this link to Thomas Aquinas Latin texts, but Pasnau warns that these are apparently based on old editions.

Bonaventure

Bonaventure’s Sentences commentary is available in Latin and English through the Franciscan Archive.

Henry of Ghent

John Duns Scotus

The Fransiscan Archive maintains a fantastic site on Scotus, replete with articles and Latin texts and translations into various languages.

14th Century and Later

Peter Aureol

Peter Aureol’s Sentences Commentary

William of Ockham

Wikisource has the Summa Logicae