What is sadness?

Is it the tension
under a mourning heart,
swinging like a pendulum
until it strikes midnight
as the stagnant eyes
close to face darkness
of loneliness?
Is it the shadow
lurking in the corner
of a crowded room
where people seem
jubilant, dancing,
chattering in mime,
but the music
doesn't break
the deafening silence,
caging it in
the narrow edge?

What is sadness?
Is it the lifeline,
a girl follows
until she finds out
it's no more, then
she seeks the way out
in the tunnel
of a mine.
Mine?
That's what she holds
and keeps inside
her heart
and the light is
a firefly, circling
until it loses
its glitter
and she is lost
into oblivion?
Is it a waste of time
the boy believes
and now, he reaches
the end of the tunnel
with his heart whole,
preparing to move on
from the rubbles
he has left inside
the mine?

The train is approaching.