This is the episode mentioned when the question of the best episode of the original series is broached and with good reason. Kirk may have the benefit of hundreds of years of knowledge, but he is left with the kind of decision that no man can make easily. This has to be the episode that inspired one of Spock's greatest pearls of wisdom, "the needs of the many outweigh the needs of the few, or the one." McCoy, mistakingly drugged, goes back in time, changes it, and makes it impossible for the crew to leave the planet they are on. They must go back and set it right, but could you let one good, forward thinking person die to save the future? The last scene in the past is haunting, McCoy has been nursed back to health by the person and tries to save them when they step into traffic, but Kirk grabs his friend and the three can only look on. The future is saved. The best episode to watch to understand what Star Trek was all about.
