According to William Shatner in Star Trek Memories, IDIC was only worked into the episode "Is There in Truth No Beauty?" as an afterthought. The actors all knew it was a mere advertising toy. Reportedly, Leonard Nimoy was asked to wear it and refused, so it was passed on to Shatner; when he also refused, Nimoy reluctantly agreed to wear it. At the last minute, Roddenberry sent down several pages of new script for the dinner scene, in which Spock was to give a long-winded explanation of the philosophy. The actors refused to film it until Roddenberry cut it down.
according to william shatner in star trek memories idic was only worked into the episode "is there in truth no beauty" as an afterthought the actors all knew it was a mere advertising toy reportedly leonard nimoy was asked to wear it and refused so it was passed on to shatner; when he also refused nimoy reluctantly agreed to wear it at the last minute roddenberry sent down several pages of new script for the dinner scene in which spock was to give a long-winded explanation of the philosophy the actors refused to film it until roddenberry cut it down