Comments by "Jim Luebke" (@jimluebke3869) on "Trope Talk: Mentors" video.
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Mentors die so much because human life is multi-generational. One generation gains wisdom with age, and another rises in an ever-replenishing fountain of enthusiasm, ignorance, and yes, potential. In many cases the whole point of stories is to show how aged wisdom combines with youthful energy (in a realistic way), not just because a mentor / student trope is the best way to bring that across, but also because older people die in the real world, and passing on that wisdom before that happens is just a much of a problem to be explored as anything else that might happen in a story.
So, aged wisdom dies, not to dismiss that wisdom, but to reflect the fact that that's the way it goes in life. Also, love interests die because up until modern medicine, childbirth was incredibly dangerous and stories are a way to explore ways to deal with this.
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