The first is the one in the title story, “Sum,” in which you “relive all your experiences, but this time, with the events re-shuffled into a new order,” and “all the moments which share a quality are grouped together.” So you sleep for 30 years, sit on the toilet for 5 years, have sex for 7 months, experience pain for 27 hours, etc. That story is a reminder that “a life where episodes are split into tiny swallowable pieces” is a well-designed and endurable one.
The second is the afterlife in “Metamorphosis,” a limbo-esque lobby the dead wait in until every single person on Earth has ceased to remember them. It starts this way: “There are three deaths: the first is when the body ceases to function. The second is when the body is consigned to the grave. The third is that moment, sometime in the future, when your name is spoken for the last time.”
I think of these three deaths whenever a loved one dies. Their first and second death has passed, but their third and final death has not, and the absolute earliest it will is at the moment my brain forgets their name. So, until my own first death, I keep them alive. This is easiest for my favorite musicians: Put on their record, and their voice fills the room.