Towards the end of the fourteenth century, a number of texts and melodies were created in Flemish Bruges which were all collected in what subsequently came to be known as the Gruuthuse manuscript. The first-known possessor and patron of this collection, Louis of Gruuthuse, probably had little to do with its creation: the manuscript was added to his library after 1474, quite a few decades after the manuscript's origin. The collection is considered to be the product of a group of Bruges music lovers, perhaps a brotherhood of upwardly mobile artisans who provided musical and theatrical assistance at masses and ceremonies. Its authors or collectors cannot be identified, although some names are revealed in the acrostics that can be spotted in the manuscript. Some of them might refer to authors of Gruuthuse texts, for example Jan Moritoen, furrier and councillor, and Jan van Hulst, messenger, illuminator, and organizer of cultural events. Jan van Hulst was also the primary architect of a brotherhood which developed into the first chamber of rhetoric in Flanders.

The Gruuthuse manuscript consists of three parts: a book of prayers, a Songbook containing 147 songs including musical notation, and a third part containing allegorical poems. ‘O brittle infirm creature’ is the hundredth poem in the Songbook. Like most texts in the Songbook, it is set to music in stroke notation, a musical notation in small vertical strokes without rhythmic specification and without matching text placement (de Loos, 2010, p. 115). It is, therefore, no small feat to decipher the melody, but it is clear that ‘O brittle infirm creature’ was meant to be performed musically. It is a song.

In this song, three different addressees are invoked with an ‘O’ apostrophe within 26 lines.4 The poem opens with one: ‘O brittle infirm creature’; the refrain, which recurs three times, is addressed at Egidius, invoked as ‘O merry soul’, and finally Fortune is apostrophized: ‘O Fortune rude, / so like the tide with ebb and flood.’ This is followed by the refrain, with the song's concluding line: ‘God's own will / not ours, prevails through good and ill.’ Along these three ‘O’ apostrophes, right to the acquiescent last line, the poet develops an entire fourteenth-century cosmos.