Heidegger's Bible Handbook: Romans: Canonical and Chronological Order of the Pauline Epistles
5. The diverse order of the arrangement and writing of the Epistles. Formerly the arrangement was also varying. The order of the Epistles according to the time of writing.
The Order of the Epistles of Paul is twofold: one of disposition or arrangement; the other of writing. The Order of arrangement that obtains in today’s exemplars appears to answer to the size of the books and also to the Churches and persons to whom they were written. For the Epistles larger, and written to entire Churches, precede: Epistles smaller, and written to individual persons follow: with the Epistle written to the Hebrews excepted, which, although surpassing in sizes most of those preceding, and written to an entire race, is set in the last place. Indeed, anciently they were not arranged by all in the same order in which they appear today. For, Saint Athanasius in his Synopsi sets the Catholic Epistles before the Pauline, and numbers that which was written to the Hebrews the tenth. But Tertullian, against Marcion, book 5, has yet another order of the Epistles. Now, with respect to the order of writing, or of time, in which each was written, that is not sufficiently evident from the Epistles themselves, nor from history. Nevertheless, since it is of no little interest to know it, and the time of the Epistles bestows much for the answering of questions, as Saint Chrysostom teaches at the beginning of his in Epistolam ad Romanos, we shall try to elicit in this place, and as far as it will be evident not to be without reason, if we hold this order of the writing, that we might say that some were written by him while he was yet free and unbound, others from his former bonds, others between his former and latter bonds, yet others from his latter bonds. By Saint Paul yet free and unbound were written: I. the first Epistle to the Thessalonians in 54 AD; II. the second Epistle to the Thessalonians in the same year; III. the Epistle to the Galatians in 59 AD; IV. the Epistle to the Romans in the same year; V. the first Epistle to the Corinthians in the same year; VI. the second Epistle to the Corinthians in 60 AD. By the same in his former bonds at Rome were written: VII. the Epistle to the Philippians in 60 AD: VIII. the Epistle to Philemon in the same year: IX. the Epistle to the Ephesians in the same year; X. the Epistle to the Hebrews in the same year. Between his former and latter bonds were written: XI. the Epistle to the Colossians in an uncertain year; XII. the former Epistle to Timothy in an uncertain year; XIII. the Epistle to Titus in an uncertain year. In his latter bonds, a little before his death, at Rome was written: XIV. the latter Epistle to Timothy in 67 AD. This Chronology, in which we have Ussher of Armagh going before us for the most part, we will demonstrate more fully in its place.