"Old people seldom talk about death, their dim eyes seem unwilling to focus anything but the past and the present. Gradually, as their memory weakens, even the past becomes more and more indistinct, and they live almost entirely in the present. That is why, granted their days are tolerably exempt from bodily suffering as nature meant them to be, old people are generally less unhappy than young people would expect them to be."
Axel Munthe: The Story of San Michele.
This perfectly describes the phase my mother has now entered.