Testing one, two, three
Scribes had to constantly adjust the nib of their quill by cutting it into the right shape. A deformed nib would not supply an even flow of ink, which resulted in letters that were not fully formed. To test if the nib was in good shape, scribes would scribble a few swirly lines or short words on an empty page. We usually find these pen trials in the back of the book, where empty pages were usually found.
The page seen here is loaded with them, including many that are written upside down, which shows just how little the scribe cared about what his pen produced during the testing phase. The most famous pen trial written in Dutch is a poem jotted down by a monk who laments how all birds are building nests, but that he, alas, is not. Anything goes for a trial.