Intolerance in the 23rd century? Improbable! If man survives that long, he will have learned to take a delight in the essential differences between men and between cultures. He will learn that differences in ideas and attitudes are a delight, part of life’s exciting variety, not something to fear. It’s a manifestation of the greatness that God, or whatever it is, gave us. This infinite variation and delight, this is part of the optimism we built into Star Trek.
Gene Roddenberry, in The Making of Star Trek (1968)