Onesimus' freely ran away from his master, having stolen from him. He then ended up in prison, only to come across Paul, whom God used to lead Onesimus to saving faith. Meanwhile Philemon has space and time to deal with what was going on in his heart toward Onesimus. Whatever exactly Paul meant by these remarks, it is clear that the time was ripe for Paul to make the appeal for forgiveness. It is assumed that Philemon himself might had been converted under Paul's ministry. Taking him back to those tender days would cause him to see God's forgiveness anew.