And thus where it is prescribed to bow reverently, it is well of the celebrant of the Mass to supplicate his Creator and Savior on his knees with the utmost devotion, reverence, and honor, to glorify Him on his knees. And this for recognizing himself to be earth and dust in consideration of so great a God with all possible humility and reverence, by which means these outward things are signs of interior things; and the Creator Himself ought to be honored and praised by His creature for the benefit of having been able to have known Him... Therefore, they are to be put to shame if perchance they should turn lukewarm, or more so, haughty and ignorant, who on this occasion do not fear with an erect neck scarcely to bend one knee to their Creator, Savior, and awesome Judge...
John Bechoffen, Quadruplex missalis expositio, (Basel, Switzerland: Michael Furter, 1505; digitized text, Bayerische Staatsbibliothek, Munich, 2007), sig. D2v-D3r), quoted in James Monti, A Sense of the Sacred: Roman Catholic Worship in the Middle Ages (San Francisco: Ignatius Press, 2013), 65. The translation into English is Monti’s own.
See also: https://bildsuche.digitale-sammlungen.de/index.html?c=viewer&bandnummer=bsb00003960&pimage=1&v=100&nav=&l=en#
(I originally found the quote in James Monti, “Late Medieval Liturgy: A Celebration of Emmanuel - ‘God with Us,’” in T&T Clark Companion to Liturgy, ed. Alcuin Reid (London: Bloomsbury T&T Clark, 2007), 96).
