For me, it was the episode Darmok.
Captain Dathon, the Tamarian captain, was a parallel of Picard. He was willing to risk his life to understand an alien life-form. The Tamarians were identical to Starfleet, desperately trying to understand "strange new life-forms". And Dathon died for it, but it worked - there was something of an understanding between the Federation and the Children of Tamar at the end of the episode.
It was always my secret hope that during one of the desperate battles of the Dominion War that we'd see Captain Dathon's old first officer, now a captain of his own ship, leading a squadron of Tamarian ships in to help the Federation, shouting "Picard and Dathon at El-Adrel!" on the viewscreen.
In fits of geekness, as a teacher, I occasionally exclaim "Sokoth! His eyes uncovered!" when a student finally grasps a particularly difficult concept...since I teach IT, most of my students are geeks themselves and appreciate the reference.
When you are dead, you don't know that you are dead. It is difficult only for others.
It's the same when you are stupid...