Desiderius Erasmus compiled the first published edition of the Greek New Testament in 1516, basing his work on several manuscripts because he did not have a single complete work and because each manuscript had small errors. In the 18th century, Johann Jakob Wettstein was one of the first biblical scholars to start cataloging biblical manuscripts. He divided the manuscripts based on the writing used (uncial, minuscule) or format (lectionaries) and based on content (Gospels, Pauline letters, Acts + General epistles, and Revelation). He assigned the uncials letters and minuscules and lectionaries numbers for each grouping of content, which resulted in manuscripts being assigned the same letter or number.