"I live now on borrowed time, waiting in the anteroom for the summons that will inevitably come. And then - I go on to the next thing, whatever it is. One doesn't, luckily, have to bother about that"

Agatha Christie's quote talks to the concept of death and the inevitability of death. She acknowledges that her time on Earth is restricted and that she is surviving on borrowed time. She is waiting for the summons that will come when her time is up, but she is not stressed over what follows. She is content to accept her fate and carry on to the next thing, whatever that may be. This quote speaks with the idea of accepting death as a natural part of life and not stressing over the unidentified. It is a suggestion to live life to the max and value the time we have on Earth. Christie's quote is a tip to maximize our time and not worry about what comes next.