John Tzetzes, Chiliades (“Thousands”) 11.393-399
“I also know specialized pearls beyond the pearls.
They shatter and release small pearls in their craft
As they roll out other pearls. These things are about pearls.
I now call books oysters full of words.
You note, I suspect, that words are the pearls that come from them.”
If for some, inexplicable, reason, you would like to read the whole poem, it is available online.