Every few years, somebody declares Star Trek has changed too much.

First, The Original Series was "real" Star Trek. Then The Next Generation wasn't. Deep Space Nine was too dark. Enterprise wasn't Trek enough. Discovery was too different. Today, Strange New Worlds is praised for feeling like classic Star Trek, while whatever series comes next will almost certainly be accused of ruining the franchise all over again.

The funny thing is, Spock (Leonard Nimoy) settled that argument back in 1969. Not with "Live long and prosper." Not during one of Kirk's grand speeches. Just eight words spoken almost in passing during the season 3 episode "Let That Be Your Last Battlefield."

"Change is the essential process of all existence."

It's the greatest quote Spock ever spoke in Star Trek: The Original Series. Not because it's the most famous, but because almost 60 years later, it still explains the character, the franchise, and even the fans who can't stop arguing about it.

What Spock's quote says about the episode

First broadcast on Jan. 10, 1969, "Let That Be Your Last Battlefield" follows the crew of the Enterprise as they encounter Bele (Frank Gorshin), whose face is black on the right side and white on the........

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