This Old Testament ‘annunciation’ prophesies the birth of Samson, one of the popular heroes of medieval story and art. There is a plenitude of evidence on this point, but his popularity could be deduced quite simply from the song which is the subject of this article. Samson dux fortissime is well known; it is often referred to, and it has been recorded at least twice in recent years. However, there is no adequate published edition of it, no comparative study of its sources and notations, and no analysis of the way in which the imposing rhetoric of its poetry is combined with an intricately patterned melody.1 This complex monophonic song offers a chance to examine melody and rhythm, rhetoric and rhyme, working together on a large scale in a harmonious and impressive whole.2