Re: 'All Our Yesterdays' theory
. . .it could also be related to Spock's comment that the cave was "agreeably warm". That could be Vulcan lingo for "Man, it's hot as hell in here!"
Spock wasn't as adept with the pick-up lines as his friend Jim Kirk. When he said the cave was "agreeably warm", he may have meant to say "let's get naked, baby!"
Curly: If at first you don't succeed, keep on suckin' til you do succeed.
--Movie Maniacs (1936)