On the paradise-like Gamma Trianguli VI, the Enterprise crew found a people kept unchanging by the machine Vaal, which tried to destroy the ship before being destroyed.
In 2267 a landing party explored Gamma Trianguli VI, a beautiful but deadly planet whose plants, rocks and weather killed several crew members. The native people lived without aging, conflict or children, serving a machine they worshipped as Vaal by feeding it. Vaal drained the Enterprise's power and pulled it toward the planet.
When Vaal needed to feed, Kirk kept the people away while the Enterprise fired its phasers on the machine, destroying it. Kirk argued that the people should now be free to grow and choose their own course, though Spock questioned the decision.