Who was Michele Zopello?

Fifty-two discoveries from the BiblioPhilly project, No. 35/52

Michele Zopello, Litterarum simulationis liber; University of Pennsylvania, Lawrence J. Schoenberg Collection, LJS 225, fol. 1r

One of the masterpieces of the Lawrence J. Schoenberg Collection at the University of Pennsylvania is the presentation copy of a work on cryptography made for Alfonso da Borgia (1378–1458) during his three-year reign as Pope Callixtus III. The text is fascinating, as it provides an unpublished and otherwise unknown insight into Renaissance systems of cyphers.

Its author, a certain Michele Zopello, demonstrates two relatively primitive methods for encrypting text based on alternate words supplied in tables, to which both communicating parties would have exclusive access. In the first system, significant words in Italian beginning with one letter are simply substituted by either of two corresponding words beginning with another letter (fols. 5v–14r). Zopello provides two sample letters plain and encrypted in order to demonstrate his method in action (fols. 14v–19r). The second system is somewhat more efficient, with unique symbols representing letters (six possibilities per vowel, three per consonant), or a whole selection of important words denoting titles, place-names, and numbers (fols.19v–20r).

During his brief pontificate, Callixtus was overwhelmingly preoccupied with countering Ottoman Turkish advances in the Mediterranean, calling for a new crusade in the wake of the fall of Constantinople. This is perhaps why Zopello furnished him with such a manuscript.  But who was Michele Zopello anyway? This manuscript made three appearances in auction and dealer catalogues in the late twentieth century, but at no point was any additional detail about this mysterious author mentioned.1 The manuscript, along with Zopello’s name, has also been cited in several works on Renaissance cryptography, but without even the slimmest additional biographical details provided.2 The author seemed a person lost to history.

However, Zopello’s identity can in fact be recovered. A person with the same name was the subject of a recent article, whose author was unaware of the Schoenberg manuscript.3 Zopello, it turns out, was an obscure figure from the town of Sacile in the Veneto who had served as secretary to Duke Louis of Savoy (r. 1440–65) from 1450. Among the scarce surviving documents relating to Zopello is the record of his official secretarial appointment, which praises his knowledge of Italian affairs and military skills, as well as letters relating to his imprisonment by Francesco Sforza in the 1450s, two of which have been put online: one letter from Sforza to the podestà of Alessandria, dated 14 September 1450, and another from Sforza to Zopello himself, dated 28 December 1452, informing him of his liberation. This documented individual, however, has never before been linked to the Zopello who is mentioned as the author of our manuscript on its first folio, even though they are clearly the same person. Tellingly, in his Latin preface to the Litterarum simulationis, Zopello describes how codes can be used to communicate with besieged cities (fols. 1r–5r). Perhaps his earlier arrest was linked to his activities as a cryptographer.

Ironically, we know somewhat more about artist responsible for the illumination on the first folio of the manuscript. The high-quality bianchi girari or white-vine decorations of the frontispiece were created by Gioacchino di Giovanni di Gigantibus (act. ca. 1450–85). Originally from Rothenberg, this professional illuminator worked for members of the papal court from 1448 onward, and his involvement would seem to indicate that Zopello was in Rome to coordinate the production of his manuscript. The intricate border designs, inhabited by three multicolored parrots and two putti bearing the wreathed crest of Pope Callixtus (or, a bull gules upon a terrace vert, in a bordure or charged with eight flames vert), demonstrate the care that went into producing handsome exemplars of even the most arcane technical tracts, in order to catch the eye and curry the favor of the intended recipient.


  1. Sotheby’s, London, 20 June 1989, lot 49; Martin Breslauer, cat. 111, 1993, no. 3; Christie’s, London, 26 June 1996, lot 19.
  2. Anthony Grafton, “Un passe-partout ai segreti di una vita: Alberti e la scrittura cifrata” in La vita e il mondo di Leon Battista Alberti: atti dei Convegni internazionali del Comitato nazionale VI centenario della nascita di Leon Battista Alberti, vol. 1 (Florence: Olschki, 2004), 6–7 (article: 3–21); Arielle Saiber, Measured Words: Computation and Writing in Renaissance Italy (Toronto: University of Toronto Press, 2017), 187 n. 8.
  3. Isidoro Soffietti, “A proposito di un segretario veneto del duca Ludovico di Savoia,” Bollettino storico-bibliografico subalpino 109 (2011): 607–14.