The kinship of shadow and loneliness is so eminent. The gaze and the haze.
The resonance of silence.  The lonely and the shadow share that
shallow existence, that yet persists and endures in careless surrender.

– I found few lines of verse for great poets on the shadow, I thought
I will add to this post./ KH
Between the idea
And the reality
Between the motion
And the act
Falls the Shadow
For Thine is the Kingdom
By T S Eliot

And, as his strength,
Failed him at length,
He met a pilgrim shadow.
“Shadow” said he,
Where can it be-
this Kingdom of Eldorado?
By Paul Laurence Dunbar

I have a little shadow that goes in and out with me,
And what can be the use of him is more than I can see.
He is very, very like me from the heels up to the head;
And I see him jump before me, when I jump into my bed.
By Robert Louis Stevenson