Colossians 4

The end of Colossians has a lot of great tidbits.

Paul refers to "chains" twice (vv. 3, 18) and that Aristarchus is a "fellow-prisoner (v. 10).  I think we can reasonably infer from this language that he wrote the letter while imprisoned in Rome.

A doctor named "Luke" is with Paul (in Rome?).  This man sends his greetings (v. 14) and I think the traditional view is that he is the Gospel writer Luke.

Paul refers to a letter from Laodicea (v. 16).  This would indicate a second letter, which appears to be lost to history.  There is an outside chance it could be the Book of Revelations by Apostle John, but I personally think Paul is referring to a letter he wrote to Laodicea that did not make it into the Scriptural canon.

The men carrying the letter to Colosse are Onesimus and Tychichus (vv. 7-9).  We know Onesimus as the escaped slave at the heart of the book of Philemon.  Putting these details together, Onesimus might be bringing two letters to the city of Colosse.  One letter is addressed to the church while the other is personally directed to Philemon.  These letters we know today as the Book of Colossians and the Book of Philemon.  

Further, the personal greetings in Colossians match those of the Book of Philemon.

Essentially, it seems the church of Colosse received both letters at once.  This escaped slave context of the Book of Philemon provides an interesting framework to view the very passages in Colossians where Paul discusses slavery.  There, he spoke at length of the requirement for slaves to obey, but only a single sentence about the reciprocal duty of a master to be fair.

Questions to ponder - is Paul implicitly saying that Philemon abused Onesimus?  If Paul focuses Colossians on obedience, why is the focus of the Book of Philemon about Philemon's forgiveness of Onesimus?  Likewise, it is silent about reinstituting Philemon's ownership of Onesimus.