In a rich and learned article, Lawrence Gushee explored the tabula monochordi of Magister Nicolaus de Luduno. The tabula, which was copied into a music theory manuscript of c. 1400 of southern Italian provenance (Rome/St. Paul), consists of three associated parts. The first and third I shall call, following Gushee, the tabula figurarum (an elaborate musical example) and the tabula numerorum (an extremely elaborate table of corresponding information). Between them lies the enigmatic text of a six-stanza musical puzzle poem, ‘Ut pateat evidenter’, with which Gushee wrestled inconclusively. A concordance to the poem unknown to Gushee in an English music theory manuscript of about the same age (Bodley 842) associates these cryptic verses with a polyphonic chanson, a two-voice ballade that has never been published. The ballade is a sophisticated demonstration piece for tonal and mensural behaviours, and I believe that this song is the original complement and key to the poem’s meaning. It also offers a significant new point of entry into the complicated world of Anglo-French tonal theory as it developed in treatises and compositions of the fourteenth century.