Publicity Photos of Leonard Nimoy as Spock in Star Trek: The Motion Picture
Here’s what Gene Roddenberry wrote about Leonard Nimoy’s character in the writer/director’s guide for the first Star Trek film.
SPOCK - At his birth, Spock’s parents made a conscious and deliberate decision to see the human half of his personality submerged in favor of following the Vulcan life-style. As we have seen in a number of episodes, this did not eradicate Spock’s emotions; it merely repressed them. As the years have gone by, this repression of one-half of Spock’s personality has taken greater and greater effort of will. Spock has become an emotional timebomb. After serving on starships for fifteen years, in close proximity to humans, he was no longer able to bear the strain and retired, at the end of the five-year mission, to recharge his Vulcanness. The process has not been working, and Spock returns for this emergency mission in a state of extreme emotional upheaval, which now seethes just below the surface of his still essentially cool Vulcan exterior.
In the course of our film, Spock will at long last come to terms with the human side of himself. He must come to recognize that he can not live his life entirely in the Vulcan mode or the human one, but must make his own individual way with no models whatsoever to fall back on. He must get to know himself as a whole being and begin the terribly painful process of losing the shame he feels whenever he feels any kind of emotion. He remains, of course, most comfortable with the Vulcan life-style, science and Vulcan philosophy, but now, for the first time, he will release some of the emotion that has been building up inside of him for these many years.
V’ger will come to learn about emotions from Spock as it is Spock’s logical mind that it can most easily relate to. V’ger, too, is something of a half-breed, being a marriage between an Earth machine and a far more advanced machine race. Spock’s torment will somewhat parallel V’ger’s confusion as it comes to grips with the full, unimaginable implications of the Earth half of its origins.