"This is one of the four Sequences which are alone retained in the revised Roman Missal, 1570, and later editions. It seems to have been written about 1260 for the Mass of the festival of Corpus Christi. For this festival St. Thomas, at the request of Pope Urban IV., drew up in 1263 the office in the Roman Breviary; and probably also that in the Roman Missal. In form this Sequence is an imitation of the 'Laudes crucis attollamus'." —"Lauda Sion Salvatorem," in A Dictionary of Hymnology, (ed.) by John Julian (1892)
