In medieval times, paper being expensively next to non-existent, the great holy books were written on more permanent velum and gloriously illuminated by monks. One of the best of these works is the magnificent "Book of Kells." And, since paper was virtually non-existent, the good monks would often make personal secular comments in the margins of the great books, often snippets of poems, droll observations about the follies and naughty doings of their fellow scribes. If you track down a CD by Samuel Barber, "Hermit Songs" you'll hear many of these snippets/poems set to music, including a lovely poem to Pangur, a scribe-monk's beloved white cat.
This poem is by Seamus Heaney from "Opened Ground; Selected Poems 1966-1996"
I never warmed to them.
If they were excellent they were petulant
and jaggy as the holly tree
they rendered down for ink.
And if I never belonged among them,
they could never deny me my place.
In the hush of the scriptorium
a black pearl kept gathering in them
like the old dry glut inside their quills.
In the margin of texts of praise
they scratched and clawed.
They snarled if the day was dark
or too much chalk had made the vellum bland
or too little left it oily.
Under the rumps of lettering
they herded myopic angers.
Resentment seeded in the uncurling
fernheads of their capitals.
Now and again I started up
miles away and saw in my absence
the sloped cursive of each back and felt them
perfect themselves against me page by page.
Let them remember this not inconsiderable
contribution to their jealous art.