The idea of one generation succeeding another involves the consequences of the passage of time, so it is appropriate that the theme of “Generations” is the central human dilemma: we live consciously in a continuous present, yet we move through time to periods of change, and ultimately, inexorably to death, which is very difficult to comprehend, to face and to keep in consciousness in our daily lives. As Braga and Moore say, this is a particularly powerful theme when dealing with heroes whose epic adventures and accomplishments are larger than life, yet they too grow old, and they also die. Can they deal with that prospect? Does it enhance their heroism, or mock it?
How Star Trek heroes deal with time and mortality is probably the most persistent single theme in the ten feature films. It is there from the first one, when Kirk struggles with his real intentions in taking over the Enterprise from his younger successor. Kirk’s aging is again a theme in Star Trek II (The Wrath of Khan), along with Spock’s death, and in III with his return to life. The possibility of being unable to adapt to change and outliving their usefulness is a topic of concern and conversation between Kirk and Spock in Star Trek VI: The Undiscovered Country (which in Star Trek is the future but in Shakespeare, it’s death.)
Time and mortality would return as a major theme in Star Trek: Insurrection, and death and change in Star Trek: Nemesis. In “Generations” it is a persistent theme linking heroes and villain, as well as linking the generations.