There's a bit in "Tomorrow is Yesterday" where Spock says something like "as the Enterprise flies towards the Sun, logically, we'll travel back in time."

Re: Space Seed, how do you get a gig as ship's historian on a deep space exploration mission? Sailing around the universe with nothing to do all day but paint pictures of your favourite dictators. Shame that when - against all reasonable expectation - something happens where her skills could come in useful, she screws…