Pauline epistles

Most scholars believe that Paul actually wrote seven of the thirteen Pauline epistles (Galatians, Romans, 1 Corinthians, 2 Corinthians, Philemon, Philippians, 1 Thessalonians), while three of the epistles in Paul's name are widely seen as pseudepigraphic (1 Timothy, 2 Timothy, and Titus).

[2] A number of scholars have argued that from biographic details from Paul, he likely suffered from some physical impediment such as vision loss or damaged hands and Paul does explicitly state, or even names, in multiple epistles that he used secretaries, which was a common practice in the Greco-Roman world; likely explaining the epistles that are seemingly non-Pauline.

The evident principle of organization is descending length of the Greek text, but keeping the three pastoral epistles addressed to individuals in a separate final section.

This practice was popularized through the 4th century Vulgate by Jerome, who was aware of ancient doubts about its authorship, and is also followed in most medieval Byzantine manuscripts with hardly any exceptions.

[27] A collection of Paul's letters circulated separately from other early Christian writings and later became part of the New Testament.