But here the question is different. Let's see... immortality, immortality... Only since Tolkien has "immortality" become associated with "eternal youth." Previously, these were different concepts: immortality = invulnerability, invincibility, but aging and eternal existence. Eternal youth means not aging, eternal existence, but vulnerability and the possibility of being killed. And almost no one (well, very few science fiction writers, etc.) ever thought about it: being immortal among the living is a terrible curse.