The poem was found in a sixteenth-century register compiled by notary Brandan de Caxario, preserved in the Notarial Archives in Valletta. One of the functions of a legal notary is to maintain a register of legal deeds and contracts which can be consulted if the parties’ copies are lost or the parties disagree.
On September 22, 1966, Dr (later Professor) Godfrey Wettinger (1929–2015) and Rev. Michael Fsadni, OP, (1916–2013) were researching, as they had done on many occasions, at the Notarial Archives of Valletta. On this occasion, they came across a poem, known as a Cantilena, written in medieval Maltese by Peter Caxaro, which was bound in the first volume of the notarial deeds published by Notary Rev. Brandan de Caxario (c. 1508–1565) between December 4, 1533, and May 26, 1536. At the end of the volume, there are eight unnumbered empty folios: the Cantilena is written on the back of folio number six.
Joseph F. Grima (22 August 2021). ‘It happened in August: Peter Caxaro and his Cantilena’. Times of Malta.
Wettinger later described the circumstances of the find:
Neither Father Fsadni nor myself was looking for specimens of Maltese poetry in the fifteenth and early sixteenth century notarial registers which we were examining. We were both, in fact, searching for documentation separately on different subjects of study—he about the early sixteenth century history of the Dominicans in Malta, I on slavery in Malta, at the same time with a longing side-glance, so to speak, at the earlier stuff so useful in understanding the social and economic condition of the people. We had frequently discussed our problems and had both remarked to each other how interesting it would be to find anything whatsoever concerning the Maltese language. Father Fsadni had already noticed certain occasional, if rare, references to the language and I was well aware of the importance of the late medieval place-names recorded plentifully in the surviving records. But that was all. When at last, on the 22nd September, 1966, the poem came to light we were astonished and excited beyond measure.
Godfrey Wettinger (3 December 1977). ‘Looking Back on “The Cantilena Of Peter Caxaro”’. Journal of Maltese Studies 12, pp. 88–89.
Wettinger and Fsadni were convinced the poem was genuine and not a forgery because it was in the handwriting of Brandan de Caxario, identical to the legal documents it was bound with:
One of our main early worries, and the first one to be solved, was the genuineness of our copy: we both had a great responsibility here—a personal one because we were and are determined not to get involved in anything the least bit shady affecting our standing as historical researchers and as men of integrity, and also a national one, because Maltese scholarship has already had to bear the burden of living with the memory of the activities of Abate Vella, who discovered so many fantastic documents supposedly dating back to Muslim times but all apparently faked by himself. In fact, the most careful examination of our document could not reveal any suspicious feature about it. Its handwriting in all its minutest details agreed fully with that in the rest of the volume, its ink was the same and had aged to the same extent and in the same way. The page on which it was written was an integral part of the register.
Wettinger, pp. 89–90.
The name of the poet was given in a Latin note by the scribe:
Our copy of the poem was undoubtedly made by Notary Brandan de Caxario in his unmistakable handwriting very different from that of anyone else on the island, then, before or after. But he attributed its composition to a Petrus de Caxario, his ancestor who was a ‘philosopher, poet and orator’ about whom I then knew nothing but whom Fsadni had already encountered as one of the benefactors of the first Dominican priory in Malta. Even then we had the difficult task of identifying our poet; could there not be others with the same name and surname? In fact there were at least four persons named Petrus or Peru Caxaru or de Caxario who lived before Brandano’s time. One was a freed man of Notary Peru Caxaru and not an ancestor of Brandano’s at all; another was a Gozitan, related distantly to Brandano but a contemporary of Brandano’s. A third was a convert from Judaism and not a relative at all. The only one who fulfilled all requirements was already known to Father Fsadni. He lived more than a generation before Brandano. It is true that he was not a direct ancestor but he could certainly be referred to quite legitimately and correctly as ‘mei maioris’ by Brandano.
Wettinger, p. 90.
Here’s a scan of the top half of the folio, showing the Latin note (which is often cropped out of reproductions), together with the first part of the poem. Below I quote Victor Bonnici’s transcription and translation of the Latin.

Aliquantulum exhilaratus [fui]1 memorans cantilenam diu compositam quondam mei maioris Petri de Caxaro philosophi poete et oratoris cui aliquando dictum fuit: confla precor calamum Caxaro clara propago; te cupiant ninphe te, tua musa curet2 quam lingua melitea hic subicio.
1 fui] supplevi.
2 curet] emendavi; curait B. Caxaro; curavit Fsadni and Wettinger.
I was made a little cheerful, in bringing to remembrance the song—composed a long time ago—of my late ancestor, Pietro de Caxaro, philosopher, poet and orator, for whom it was once said,
Blow a reed-pipe for Caxaro, divine offspring, I entreat;
For you may the Nymphs long, for you may thy Muse care,
which (song) I here set down by means of the Maltese tongue.
Victor Bonnici (2015). ‘On the Latin Introduction to Caxaro’s Cantilena’, p. 106. Malta Classic Association.