There is one major difference in the role of Heaven's messengers, which sets them off from those the world appoints. The messages that they deliver are intended first for them. And it is only as they can accept them for themselves that they become able to bring them further, and to give them everywhere that they were meant to be. Like earthly messengers, they did not write the messages they bear, but they become their first receivers in the truest sense, receiving to prepare themselves to give.
That was from Lesson 154 in the Workbook, "I am among the ministers of God." Although, that's not where I was reading it since I'm on Lesson 7, and I'm following the rules of not doing more than one set of exercises per day. That particular rule may just apply the first time through, but heck, I'm a compulsive rule follower, probably.
Anyway, I just read that tonight in The Disappearance of the Universe, chapter 15, right near the end. I love that quote, and it is also a good reminder to me of who is the student and who is the Teacher.