Also, Bread and Circuses was co-written by Coon and GR. Anybody know who did what on that episode? I suspect that Coon's touch was the round-table dialogue about cultural relativity and the World Wars, while GR probably brought in the worship of the Sun/Son.
There's a great memo reprinted in one of the sacred texts (was it the David Alexander book?) from Gene Coon to the WGA, where he asks that John Knuebehl, who was originally credited with the B&C story (I think this survives to the Blish adaptation) be removed from the credits of that episode. He discusses in some detail how he and Gene Roddenberry totally "rebooted" the episode because Knuebhel was too sick to deliver, and that they deserved the sole credit.
He does not delineate who wrote what, but he gives Roddenberry equal mention.
My bet is that is was a Roddenberry idea, Coon did most of the scripting, except perhaps the Drucilla stuff ("they threw me a few curves") and the son up in the sky business.
Pure speculation on my part. It has been hinted that, since this was Coon's last episode (well, actually, he got credit for Private Little War which was filmed AFTER Journey to Babel, a Lucas outing--I never figured that out) some kind of bad blood arose between him and GR, possibly due to GR's "butting in" and taking credit (and payment) for B&C. But again, this is nothing but gossip.
I really, really, need to get a life.