This subject is unto the foulest pen,
Or fairest handled by the sons of men.
'Twill also show what is upon it writ,
Be it wisely, or nonsense for want of wit,
Each blot and blur it also will expose
To thy next readers, be they friends or foes.

Comparison.

Some souls are like unto this blank or sheet,
Though not in whiteness. The next man they meet,
If wise or fool, debauched or deluder,
Or what you will, the dangerous intruder
May write thereon, to cause that man to err
In doctrine or in life, with blot and blur.
Nor will that soul conceal from who observes,
But show how foul it is, wherein it swerves.
A reading man may know who was the writer,
And, by the hellish nonsense, the inditer.

John Bunyan

http://www.poemhunter.com/poem/upon-a-sheet-of-white-paper/