Star Trek Original Series V. 39

The Savage Curtain: (Episode 77)
While surveying a planet composed of lava, the crew of the U.S.S. Enterprise is startled when Abraham Lincoln requests permission to board!Intrigued, Kirk affords him due honors; then he and Spock follow Lincoln to the planet where they meet Yarnek, a rock creature.Yarnek pits the "good" men against an equal number of tyrants, representing "evil,"so his race can learn who is stronger.The stakes are high: if Kirk loses, Yarnek will destroy the U.S.S. Enterprise.

All Our Yesterdays: (Episode 78)
Kirk, Spock and McCoy beam down to Sarpeidon to rescue inhabitants before its sun explodes.But they arrive to find only the planet's librarian, who has helped all the others to safety via a time machine.When Kirk accidentally enters the past, Spock and McCoy attempt a rescue, emerging in a bitter ice age!Spock, now a throwback to earlier Vulcan times, falls in love with a beautiful woman and has no intention of returning to Kirk or the U.S.S Enterprise.