2014-03-06 6:34 GMT+01:00 Greg Ewing <greg.ewing@canterbury.ac.nz>:

The point of having time objects as an abstraction is
so that you *don't* have to think of them as an offset
from anything. You simply think of them as times.

but times *are* offsets from midnight (24h clock) or midnight and noon (12h clock)

1 o’clock = 1 hour after midnight

12 o’clock pm = 12 hours after noon

they are essentially radial coordinates – and radial coordinates do have a 0 point.