[19.] Clark, _The Abbey of St. Gall etc._, 112; C. Diehl, _Manuel d’Art Byzantin_ (Paris, 1910) 359-360, 362-3; M. Hauttmann, _Die Kunst des frühen Mittelalters_ (Berlin, 1929) 51-62; J. Strzygowski, _Origin of Christian Church Art_ (Oxford, 1923) 84. [20.] _Anal. Hymn._, 51, _Introduction_, xvii-xix; extended lists of the later Latin hymns appear in J. Julian, _Dictionary of Hymnology_ (London, 1925) 546, 547. [21.] J. Mearns, _Early Latin Hymnaries_ (Cambridge, 1913). [22.] Walpole, _Early Latin Hymns_, (ch. 1, note 3) xi. [23.] Walpole, _ibid_, xii; W. H. Frere, Introduction to _Hymns Ancient and Modern Historical Edition_ (London, 1909); Wilmart, _Le Psautier de la Reine etc_., 362-3; F. J. E. Raby, _Christian Latin Poetry_ (Oxford, 1927) 38-41. See also R. E. Messenger, “Whence the Ninth Century Hymnal?,” _TAPhA 69_ (1938) 446-464. [24.] Gesta Caroli, I, 10; Einhard, _Vita Caroli_, edited by Garrod and Mowat (Oxford, 1915), Appendix, p. xxxvii. [25.] Heimbucher, _Die Orden und Congregationen_ etc., vol. I, 235, 237-9; _Jahrbücher der deutschen Geschichte_ (Berlin & Leipzig, 1866-1902), _Geschichte des Ostfrankischen Reichs_, vol. II, 39, 42, 46. [26.] Alcuin, _De psalmorum usu_ (_MPL_, 101), _Officia per ferias MPL_, 101, _Epistolae_ 84, 94, 164, 227 (_MPL_, 101): Rabanus Maurus, _De clericis institutés_, II, 49 (_MPL_, 107, 362): Amalarius of Metz, _De officiis divinis_ (continuation) in J. Mabillon, _Vetera Analecta_ (Paris, 1723) 99; Walafrid Strabo, _De ecclesiasticarum rerum exordiis_ etc., ch. xxv (_MPL_, 114, 952ff.). [27.] H. De Boor, _Die deutsche Literatur_ 770-1170 (München, 1949) 21. [28.] P. Batiffol, _History of the Roman Breviary_ (London, 1912) 143-4. [29.] _Anal. Hymn_. 51. [30.] Translation of first line, J. M. Neale. [31.] Dom P. B. Gams, _Die Kirchengeschichte von Spanien_ (Regensburg, 1862-1879) II, Pt. 2, 302, 326-9; Z. García Villada, _Historia eclesiástica de España_ (Madrid, 1929-36) V, 85. [32.] De Urbel, “Los himnos mozárabes,” _Revista ecles. Silos_ 58 (1927) 56-61. [33.] E. Bishop, “Spanish Symptoms,” _Liturgica Historica_ (Oxford, 1918) 168. [34.] L. Wiener, _Contributions toward a History of Arabico-Gothic Culture_ (New York, 1917-21) 101; H. G. Farmer, _Historical Facts for the Arabian Musical Influence_ (London, 1930) 23. [35.] _Anal. Hymn_. 51, _Introduction_. Chapter Four The Ninth Century Revival: Sequences [1.] Fortescue, _The Mass_ (See ch. 3, note 8) 268-9. [2.] See _Introduction_ to _A. H._ 53, by C. Blume and H. M. Bannister. This _Introduction_ has been used as the basis for the discussion of sequence origins. Theories and opinions of others are noted from time to time.