At the dawn of the Renaissance, Liber Catulli was difficult to read not only for the text but also for the arrangement of the poems: few were identified, even less had titles or graphical devices to mark them. After a century, nevertheless, the book became a poetic collection in modern terms: what happened?This work provides an overview of the process, comparing paratestual evidences in latest manuscripts and first printed editions of Catullus, in order to better understand his concrete transmission, types of book or poem titles used by scribes and their relations with the meaning of the text. Following a time criterion, the author collected the most relevant paratextual facts in witnesses, searching for the innovations and constants: the first seems to coincide with philological vanguards of the XV century, while the second sheds useful lights on contamination phenomenon, that deeply affects the transmission of Catullus. This book helps to trace an outline of the comprehension of the poems and fata libelli from the late XIV to early XVI century.