"And you run and you run to catch up with the sun but it's sinking
Racing around, to come up behind you again.
The sun is the same in a relative way, but you're older
Shorter of breath, and one day closer to death."
-- PF, Time (DSOTM) 1972.

Each time we breathe, is it just one more breath, or rather, one breath less? I have found the way I see life depends, in a way, on how I believe the Set of my breaths and heartbeats is constructed: if it is already given, if they are already counted, then I should follow by the line the previous verses, and I turn out to be a delightful pessimist. If, on the other hand, that Set is not given, but is constructed by ourselves, element by element, then the previous verses would simply recall clocks and ticks and alarms, and a nice song, and I turn out to be a delighted optimist.