In the thousands of registers preserved in the Archives dating from the start of the Duomo's construction, it is not uncommon to come across those that in codicology are known as probationes calami: drawings, phrases, or simple words, that the person who completed the register jotted down on the blank pages at the beginning or the end in order to test the point of the quill or to practice a certain style of penmanship.
They are often words or symbols that have nothing to do with the content of the register, as in the case of these two photographs, which show two pages from two separate registers dating form the 15th century.
On the left (REG. 599) the scribe practiced with the proverb Chi asino è et cervo essere se crede / al saltare de la fossa se n’av(v)ede [He who believes himself incredibly capable, but is not / realises it when he is put to the test.]; while on the right (REG. 600) we find a drawing of a greyhound.