Jacques Paul Migne’s Patrologiae Cursus Completus: Series Latina forms the largest collection ever published of the extant writings of the Latin Fathers and Doctors of the early and medieval Church. It served as the translation base for Philip Schaff’s Early Church Fathers and has been the bedrock for theological and historical studies of the time period extending from Tertullian in AD 200 to Pope Innocent III in AD 1216.
Between 1844 and 1864, the abbé Jacques Paul Migne, an industrious French priest, published the 221 volumes that make up the Patrologiae Cursus Completus: Series Latina, roughly translated “Complete Course on Patrology, Latin Series,” and commonly referred to as “Patrologia Latina” (PL). These volumes contain much of the available witness in Latin to the writings of the Fathers and Doctors of the early and medieval Church. Each volume of the Patrologia Latina contains not only the Latin editions, but also lengthy dissertations, introductions, critical apparatuses, and other supplementary material written in Latin.
The 38-volume edition of the Early Church Fathers, edited by Philip Schaff, used many of the Patrologia Latina volumes as its translation base, but the Patrologia Latina contains many works of the Church Fathers not translated by Schaff and not available in English. With the Patrologia Latina, you can read and research valuable but difficult-to-find works, like the important writings by Radbertus and Ratramnus in the ninth century on the Eucharist, which contain the earliest debate on the doctrine of transubstantiation and provide a window into this doctrine's emergence and development.
For those who have the Logos editions of Schaff’s Early Church Fathers, the Patrologia Latina encodes links to the material in common, allowing access to an English translation. More importantly, for those wanting to read the texts translated by Schaff in their original language, the Patrologia Latina is a must.
These volumes are not facsimile editions of page-scans; they are full-blown, full-text Logos resources. Search, for example, for every occurrence of the word “filioque” to trace the important debate surrounding the procession of the Holy Spirit from the Son, which contributed to the Great Schism of 1054 between the Eastern and Western Churches. Search for “facienti quod en se est” to look for discussions on Franciscan pactum theology, which was so important for the controversies surrounding the Reformation era. (Morphological tagging may be added later depending on interest.) Each volume of the Patrologia Latina is navigable by page number or column number (the primary method of citation of the Patrologia Latina), linked to many Logos books, and indexed by author and work. Further detail (chapter, section, verse) will depend upon each work itself and reflect the divisions marked by Migne.