what it really was about

"Captain to crew: Those of you who have served for long on this vessel have encountered alien life-forms. You know the greatest danger facing us is... ourselves, and irrational fear of the unknown. There's no such thing as 'the unknown', only things temporarily hidden, temporarily not understood."

"You represent Earth's best, then?"
"No, sir, I'm not. I'll make plenty of mistakes."
"But you'd find out more about us that way. And I'd get a better officer in return."