The Patrologia Latina Database contains 221 volumes and represents a complete electronic version of the first edition of Jacques-Paul Migne's Patrologia Latina (1844-1855 and 1862-1865).

Migne's Patrologia Latina was originally printed in 217 volumes from 1844 to 1855. There were two series: the series prima, volumes 1-73, (Tertullian to Gregory the Great), 1844 -1849; and the series secunda volumes 74-217, (Gregory the Great to Pope Innocent 3rd), 1849-1855.

Therefore the main chronological sequence of authors in the Patrologia Latina runs from about AD 200 to AD 1216. However Migne did incorporate medieval texts written after 1216 where these were traditionally attached to an earlier work, often as a commentary or an introduction to it.

While wanting to respect Migne's evident wishes, we have felt it necessary to distinguish roughly between the medieval and modern authors contained in the database. This division allows searches excluding, or solely in, modern texts.

We have categorised authors as medieval and modern according to modern scholarly practice by taking the year 1500 as our guide. Although this year cannot definitively mark the end of the "medieval" and the beginning of the "modern" age, it does capture the sense of the two terms for modern scholarship.