Preparing the parchment was a delicate business.
This was the most delicate part.
These pages (pictured above)are from a 14th-century book.
Repairing holes this way was a common practice, especially in some monastic communities.
The hole is perfectly aligned over a drawing of a dragon on the next page.
At other times, holes are cleverly incorporated into art.
This image shows a page with three holes that was turned into the face of a laughing man.
Sources:erikkwakkel.tumblr.com/Uppsala University Library/medievalbooks.nl