”The manuscript Amb.L.22 suss., which can be dated in general between the end of the six teen and the beginning of the seventeenth century, contains a collection of lives of the saints copied from earlier manuscripts. The preface to this collection, written by cardinal Federico Borromeo, contains some interesting remarks on the reasons for the destruction of ancient texts, on the use of the roll and on miscellanies. Using this material and other passages from Federico`s works, in which he provides explanations of the meaning of the classical terms liber, tomus, caput, the article illustrates Federico`s interest in the history of the book. Particular attention is paid to the introduction, attributable to Federico, to a second collection of lives of the saints (ms. Ambr. F 17 inf.) in which the founder of the Biblioteca Ambrosiana claims that calligraphic analysis is a valid instrument in the dating of manuscripts”.