By Cause

I cannot look directly at the sun
Yet I am sure it shines, since I can see;
The air I breathe is visible to none
Nor can I show the proof of gravity
Except to say I'm still upon the ground
And breathing, so they both are surely here,
Just as the ambience of petty sound
Proves something presses on my waiting ear.
The wind unseen can cut, afflict, or balm,
Demonstrating as it does its presence
Remembered even in the dead of calm
Despite frustration at its evanescence
So is it, love, observing you apart:
You must exist, since I still have a heart.