A ray of light, to an oblique observer, 
Remains invisible in pure dry air; 
But shone into a turbid element 
It throws distracting side-gleams everywhere 

And is diminished by what takes the eye. 
So poetry that moves by chance collision 
Scatters its brightness at each random mote 
And mars the lucid order of its vision. 

The purest meditation will appear 
Faint or invisible to those who glance 
Obliquely at its unreflected beam;