Aeterni Festi gaudia. Adam of St. Victor. [St. Augustine.] The earliest form of this sequence, which dates from the 12th century, is in a Rheinau manuscript of the 13th century, cited by Morel, p. 203, where it reads "Interni festi gaudia". This reading is followed by Daniel, ii. p. 250; Kehrein, No. 502; and others. L. Gautier, who printed from a 14th century manuscript at Paris, gives the opening line as above— "Aeterni festi gaudia," the first word being the only change throughout the sequence. The full text, together with notes, is given in …Wrangham's reprint, The Liturgical Poetry of Adam of St. Victor, 1881, vol. ii. pp. 186-191. Dr. Neale says:—
"Gautier reads Aeterni, but I understand the poet to mean that the external celebration of the Festival is only the outspoken expression of the internal joy of the heart." Mediaeval Hymns, 3rd edition 1867, p. 133.
[Rev. W. A. Shoults, B. D.]
2. The praises that the Blessed know. This is a second cento by Dr. Neale. It appeared in the Hymnal Noted, with the foregoing, and is composed of stanzas x., xi., vii., vi. and xiii. in the order named; and begins with the Latin stanza "Harum laudum praeconia." It is repeated with stanzas xii. for vi. in the People's Hymnal, 1867, No. 277.
--Excerpts from John Julian, Dictionary of Hymnology (1907)