score:2
It was actually a marginal note at the end of a manuscript of St. Gregory the Great's Moralia in Job by 10th century copyist Florentius of Valeránica:
Because one who does not know how to write thinks it no labor, I will describe it for you, if you want to know how great the burden of writing: it mists the eyes, it curves the back, it breaks the belly and the ribs, it fills the kidneys with pain, and the body with all kinds of suffering. … As the last port is sweet to the sailor, so the last line to the scribe.
—John Willinsky, The Intellectual Properties of Learning: A Prehistory From Saint Jerome to John Locke, p. 40, quote from Introduction to Manuscript Studies p. 23, from Madrid Biblioteca Nacional MS 80.
Also, St. Thomas Aquinas, Summa Theologica II-II q. 188 a. 5 co.:
…the toil that study entails according to Ecclus. 31:1, "Watching for riches consumeth the flesh."