Paul's letters
Paul's letters, totaling 13, are remarkably preserved letters (also called Epistles) by Saint Paul, four of which (31%) were from prison, to the early Christian communities prior to 64-65 A.D., when Paul was executed by pagan Romans. The New Testament includes 13 of Paul's letters, not ordered by chronology. The first letter is traditionally thought to have been his First Epistle to the Thessalonians, while there is also strong evidence that his earliest was his Epistle to the Galatians. The total word count of all 13 letters is 26,236 words in their original Greek.
Paul was a movement conservative who was a hardliner on many issues.
Paul's "Prison Epistles" were Ephesians, Philippians, Colossians, and Philemon. The additional nine letters by Paul were his Romans (ordered first in the collection because of its significance), 1st and 2nd Corinthians, 1st and 2nd Thessalonians, 1st and 2nd Timothy, Galatians, and Titus.
Their ordering in the New Testament is as follows: Romans, 1 Corinthians, 2 Corinthians, Galatians, Ephesians, Philippians, Colossians, 1 Thessalonians, 2 Thessalonians, 1 Timothy, 2 Timothy, Titus, and Philemon.
Paul's letters confirm the very early origin of the Gospels by referring almost verbatim several times to passages in them.