Final answer:
The death of Captain Karsavin signifies the idea of mortality and the inevitability of death.
Step-by-step explanation:
The death of Captain Karsavin represents the idea of mortality and the inevitability of death. In the given text, the captain's reflection on his potential demise highlights his realization that death is a natural part of life, and he questions the purpose of his journey if it ends in death. The mention of other deaths and the mourning of fallen comrades further emphasizes the theme of mortality.