“Return to Tomorrow” is a sad little tale – not really in the fact that it is a tragedy, but in the fact that it starts out strong and compelling but then decomposes into a hot mess that throws out all the rules and the intrigue that it set up.
This is where the tragedy of the episode comes it. The alien’s quest to reacquaint themselves with sensations and emotions is compelling, Nimoy gives a great performance that allows him to break from the norm, and there is a speech that is really good even if Shatner hams it up a little too much.
Interesting Fact: This is the first mention aired in Star Trek of the concept that humanoids are prevalent throughout the galaxy because they are descendants of a race that “seeded” them. In the Next Generation episode “The Chase”, it is confirmed that humanoids were “seeded” as Sargon described, although Sargon’s people are not specifically named as responsible.
“They used to say, if man could fly, he’d have wings. But he did fly; he discovered he had to. Do you wish that the first Apollo mission hadn’t reached the moon, or that we hadn’t gone on to Mars and then to the nearest star? That’s like saying you wish that you still operated with scalpels and sewed your patients up with catgut, like your great, great, great-grandfather used to do… Dr. McCoy is right in pointing out the enormous danger potential in any contact with life and intelligence as fantastically advanced as this. But I must point out that the possibilities–the potential for knowledge and advancement is equally great. Risk–risk is our business.”