The textual edition of this motet is based on one source, Librone 3, ff. 131v–132r, where the motet was written by Scribe I. No mistakes were made by the scribe except for the substitution of the word ‘mater’ for mitis in C.
Devotion to Mary is the predominant topic in this motet as well, except for the first portion of the text. This clearly did not represent a problem for the composer in spite of the fact that this motet was intended for the elevation, as the loco rubric Ad elevationem at the top of fol. 131v indicates. On the other hand, the Christological prayer with which the text opens (‘Adoramus te, Christe…’) clearly hints at the intended liturgical position of the motet. This prayer, widespread and often combined with other prayers, was used on various occasions. At least one source, a fifteenth-century book of hours from Lille – Bibl. municipale, MS 14 (a.c.69)^[1] – explicitly mentions it as an Elevation prayer with the rubric: ‘In elevatione corporis sanctissimi DNIC humiliter inclinatus percutiendo pectus tuum dic’, which translates as: ‘Say this prayer while you humbly bow and while beating your breast at the Elevation of the body of our most holy Lord Jesus Christ.’
The subsequent verses are drawn from various Marian sequences, Ave virgo virginum (AH 54, no. 285, p. 432) for ‘Ave virgo … Peccatorum venia’ and Mariae praeconio (AH 54, no. 249, p. 391) for ‘Tu pincerna … es regina’, with some interpolations.

^[1] See Giacomo Baroffio, ‘Corpus italicum precum: Materiali per una storia del sentimento religioso in Italia’, http://www.hymnos.sardegna.it/iter/iterliturgicum.htm.