something I stumbled upon while reading

There is a sort of busy worm,
That will the fairest book deform.
Their tasteless tooth will tear and taint
The poet, patriot, sage or saint,
Nor sparing wit nor learning.
Now, if you'd know the reason why,
The best of reasons I'll supply:
'Tis bread to the poor vermin.
~J Doraston, quoted by W. Blades, Taken from Inkheart