LAUDA SION SALVATOREM. - Sequence of the Mass of Corpus Christi, composed by St. Thomas Aquinas, probably at Orvieto in 1264, on the occasion of the bull Transiturus, with which Urban IV established the Eucharistic solemnity for the whole Church, in imitation of the feast instituted at Liège in 1246 by Bishop Robert de Torote under the influence of the revelations of Bl. Juliana of Cornillon (v.).
The attribution of the Office and the Mass (in which the sequence is contained) to St. Thomas was contested by the Bollandist D. Papebroch (Acta SS. Aprilis, I, Antwerp 1675, p. 903 ff.), but was immediately reclaimed by the Dominicans J. de Maison (Dissertatio historica pro officio Corporis Christi Divi Thomae, 3rd ed. Paris 1679) and A. Natalia (Dissertationes historicae et criticae quibus officium ven. Sacramenti s. Thomae vindicatur, Paris 1680), a reclamation accepted by Papebroch himself (Conatus chronologico-historicus ad universum seriem Romanorum pontificum. Propylaeum ad Acta SS. Maii, Antwerp 1688, pp. 374-376: there is found the dissertatio XLIII alias XXIII: De officio pro festo Corporis Christi Urbani IV inusu per s. Thomam composito. Furthermore, in the Acta Sanctorum Bollandiana apologeticis libris in unum volumen nunc primum contractis vindicata, ibid. 1755, pp. 438-43, the Accusatio contra Papebrochium is reproduced, followed by a Responsio). Today criticism is decidedly favorable to the Dominican thesis, since the precious testimony of the contemporary and friend of St. Thomas, Ptolemy of Lucca, cannot be diminished by the late liturgical appearance of the office; this delay in fact finds a satisfactory explanation in the special historical circumstances: after the death of Urban IV, the Holy See, totally absorbed by the great difficulties of the moment, was unable to watch over the application of the bull Transiturus; only after the Council of Vienne (1511), where Clement V had called back into force the provisions of Urban IV, did the feast of Corpus Christi begin to spread, which was therefore called nova solennitas, and since neither Urban nor Clement had imposed the office composed by St. Thomas, this appeared only a few decades later and became almost universal, rapidly replacing, because of the superiority of its content and the growing prestige of its author, the Office and the Mass which the Roman Curia had to use before accepting the work of the Aquinate (cf. F. Baix-C. Lambot, La dévotion à l'Eucharistie, Gembloux-Namur 1946, p. 94).
The sequence, only verbally inspired by the hymns of Adam of St. Victor, is composed of 24 stanzas, which follow one another with tight logic: after the solemn opening consisting of a pressing invitation to praise and joy (1-5), the rhythm expands into the rapid evocation of the shadows of the Old Testament (6-8), finding fulfillment in the Eucharist (9-10), which, multiplying in the mystery of Transubstantiation the presence of Christ "non conclusus, non confractus, non divisus," makes him food for all souls (11-15), which draw fruits of life or of death according to the dispositions with which they receive him (16-20). A moved cry of admiration (ecce panis Angelorum) and a tender prayer to the Divine Shepherd conclude this luminous and geometric composition, surrounded by the fervor of an immense love.
The symmetry of the L. S. is not artificial, but is born from the logical interiority of the thought: it is the Gothic of poetry; just as the cathedral of Cologne is a powerful bundle of spare lines stretching toward the sky, almost arms in prayer, so the rhythm of St. Thomas rises in the concept-laden linearity of the wording toward the spaces of high speculation, to be transformed, with lyrical impetus, into a warm entreaty. These stanzas, so limpid as to form so many articles of a perfect Eucharistic creed, so robust as to be held verses cast in bronze, constitute the pearl of the Catholic liturgy and make their author the "Eucharistiae praeco et vates maximus" (Pius XI, encyclical Studiorum ducem, 29 Sept. 1923; in AAS, 15 [1923], p. 320).