The poem Lauda Sion was composed in the 13th century by Canoness Juliana of Liège.
She had visions which drew her attention to the fact that there was as yet no text celebrating the Eucharist: the body and blood of Christ. Her friend and colleague, Canon John of Lausanne, brought her visions to the attention of Pope Urban IV who gave his approbation. So she composed the poem Lauda Sion with his blessing and it formed the basis of the new Feast of Corpus Christi.