Never mind later this week -- found it!
TO: Fred Freiberger
FROM: Gene Roddenberry
DATE: May 23, 1968
SUBJECT: “Wink of an Eye” Story Outline 3/22/68 by Lee Cronin
(excerpted from a 3-page story memo)
I think also he will see that we don’t have enough inter-character relationships among our continuing people. We need conflicts, disagreements, rich personality relationship between Kirk, Spock, McCoy and others. Otherwise, our “television family group” becomes a rather uninteresting assortment of similar individuals who stand around throwing each other lines and generally agreeing with each other.
Of course, Roddenberry reversed his position on inter-character conflict twenty years later, which, ironically, caused quite a bit of inter-personal conflict behind the scenes of Star Trek: The Next Generation