One of the best of Star Trek episodes is this one when the Enterprise comes upon a superior alien race that select the landing party of William Shatner, Leonard Nimoy, DeForest Kelley and a pair of unnamed crewmen as guinea pigs in a psychological experiment. The aliens look like second cousins to the Talosians and we know what intellects they had. You also know what happens to unnamed crewmen in any Star Trek episode.
This crowd is almost as good or bad depending on your point of view. The three regulars are put into a room together with a deaf mute named Gem played by Kathryn Hays. She cannot speak, but her facial expressions tell much because Hays is a total empath with healing powers. As all the series regulars are tortured, Hays heals them. But like that other healer from the big screen, John Coffey in The Green Mile it takes a lot out of Hays every time she heals. It's soon clear she's the object of the alien experiment.
As Kirk tells them at the end these experiments are futile because these aliens have evolved into pure intellect, way beyond even that noted Enterprise intellect Spock. Empathy is not something you can objectively analyze. You either have it or you don't. A little more empathy, a little less intellect without sacrificing too much is what this old world needs.
Nice issues are developed in this fine Star Trek story.