http://biblehub.com/greek/3623.htm
Stop crying. Tam and others have it right, you don't. Paul is God's sole appointed manager/administrator/steward of the revelation of this dispensation of grace. He alone claimed to be; no other apostle did because they weren't. Paul exalted that office; no one else did because they hadn't been given it.
I think I can help support this final point by noticing a couple things about Rom 16's finale on this. It was indeed God who already had the grace of the Gospel in OT Scripture. It was him alone who un-hid this at his chosen time--the launch of the Christian body.
2nd, it is very important to see the word choice about how this is disclosed. There is an administrative term used 'a royal order' but it is not verbal. God doesn't just say "(a doctrine)" this time--although it will be expressed at various passages Paul will write. He makes it
happen. The nations are responding and becoming Christians. They are doing so because the trappings of Judaism are out of the way. The righteousness of God is now known to be transfered direct from Christ instead of 'through the Law.' It is the righteousness that is 'apart from Law' (as an administrative vehicle), Rom 3:21.
Judaism always knew there would be a mission to the nations, but they thought it was through the Law. In the intertestament period, you see (based on how strict Ezra and Nehemiah modeled) that this is where they thought everything was going; an age of Law was ahead and leaders in Judaism would be its teachers and missionaries.
So the most daring, or surprising, statement of Paul is Eph 3:5 when he says that everything promised to happen to Israel was finding its fulfilment 'through the Gospel.' That's the exact spot where Judaism would have thought 'through the Law.'
[sorry there is more italicized than I wanted and I can't fix it]