Breathing out and in

My planet is a bubble
in an endless cosmic sea.
Exactly where we are
is a mystery to me,
as incomprehensible as time.

I see the pin-point stars,
the next-door-neighbor moon,
and feel the universal pulse
in every vein.

On this planet we all
breathe the same air,
drink the same rain,
feel the same sun on our skin.

And I wonder
who breathes in when I breathe out?
who breathes out when I breathe in?