For perhaps he (Onesimus) was for this reason parted from you for a while, that you should have him back forever, no longer as a slave, but more than a slave, a beloved brother, especially to me, but how much more to you, both in the flesh and in the Lord.
The reason Onesimus left Philemon was that he did not want to be a slave and ran away, which was a serious thing in those days. Yet, in God's sovereign plan Onesimus met Paul and became a believer. Now Paul is sending him back to work for Philemon not just as a slave but now a brother in Christ.
What stands out to me in this account is the eternal perspective Paul has and is explaining to Philemon. He escaped from being a slave but he did so in order to become a believer. I am sure he went through some tough situations but it was worth all the pain for what God had in store for him.
So what do I learn from this? There are things that happen in my life and in the life of others that seems to be bad and filled with problems. Yet, God has a purpose that is beneficial to everyone because He is the blessed controller of all things. He is God Almighty the Sovereign Lord of all. Lord, help me to maintain this perspective as I go through life and as I seek to help others in their lives.