Not Enough

My lips utter a single
Sad note--ringing in the pale
Light then die,
The note that ticks
Through my head is that
"I'm not enough"
And oh do I know 
That I am not--I know very well
Of what I'm dying of,
In the darkness of my heart
I will not let you see
Lest you see what my heart
Pumps through my veins.