What creature is this? That follows both in the daylight and the night

In the shadows of my footsteps, lurking in vague corners on the edge of my sight,

Never wanting for anything, no demands does it make

Always there, in formless guise a thing that I am unable to shake

Is this myself or some other machine?

Strange individual obscure, terrible, obscene

What reflection would show in polished mirror so clean?

What mask or face would my eyes reveal and glean?

I know not, I dare not, my spirits wish not to reveal

I look away and forget, let such things themselves so conceal.