"All Our Yesterdays" is the twenty-third and penultimate episode of the third season of the American science fiction television series Star Trek.
Aware of the imminent destruction, Atoz tells the landing party that he will soon rejoin his family.
Kirk finds himself in a period similar to 17th century England while McCoy and Spock travel back 5,000 years to Sarpeidon's ice age.
Spock displays uncharacteristic emotionalism, falling in love with Zarabeth and growing angered by McCoy's slurs.
McCoy realizes that being brought into the past is causing Spock to revert to the barbarism of the ancient Vulcans.
Unwilling to leave Zarabeth, and unaware he will die if he remains in the past, Spock tries sending McCoy through the portal alone.
The episode had its origins in Jean Lisette Aroeste's story outline A Handful of Dust.
[3] In 2016, SyFy ranked "All Our Yesterdays" as the 12th-best time travel plot of all episodes of the Star Trek franchise.
[4] A 2018 Star Trek binge-watching guide by Den of Geek, recommended this episode for featuring the trio of characters Kirk, Spock, and Bones of the original series.
[8] This episode was released in Japan on December 21, 1993 as part of the complete season 3 LaserDisc set, Star Trek: Original Series log.3.