What it means to be human. One of the biggest center pieces of many science fiction stories, let alone stories in general. But when it comes to Star Trek, does being human have to be restricted to the human species? I always think back to that exchange in Star Trek VI.
Kirk: Spock, you want to know something? Everybody's human.
Spock: I find that remark... insulting.
I took that as Kirk's admission that being human is not exclusive to the human race since Kirk had to get over his deep prejudice towards the Klingons. He thought they were nothing but blood thirsty animals, but when he met Gorkon, a Klingon who wanted peace with the Federation and didn't want to end things in bloodshed, he saw something different. You see, I think a lot of writers seem to miss on the point that what makes us human doesn't mean it has to be about us.
Like for example, Data's entire journey throughout TNG and the movies has been wanting to be human.
Data: I am superior, sir, in many ways. But I would gladly give it up to be human.
Why? Why does he wish to become something that he is not? Why can't he be happy with who he is while still maintaining the characteristics of wanting to be a better person? What is it about being an android that makes him so unhappy that he's willing give up everything? Is accepting who you are and what makes you special a bad thing in Star Trek? That's not a very good message.