diminutive of the Italian libro, and meaning ' little book,' is the term generally used to denote the text of an opera or oratorio, but more especially the former. Libretti have undergone many changes in style and character corresponding to changes in musical development ; indeed the librettist has frequently played nearly as important a part in such developments as the composer. An opera libretto is to all intents and purposes a stage play cast in a certain mould, conditioned by musical requirements, and it may be noted that it was really the development of the aria and the formal musical number which marked the first differentiation. Thus the early Florentine experimenters in the opera form would employ their musica parlante in their setting of the text of a play, so that the librettist as such did not come into his own until it was found necessary for the composer to break the monotony of his recitative with moments of purely lyrical expression. Thus arose the aria for which the poem had to be provided, and the difficulty with which the librettist was confronted, owing to the claims of the singers, in maintaining a proper balance between musical and dramatic interest, a balance which Gluck and Calzabigi sought to restore after the type represented by Metastasio's libretti had become prevalent. In later operatic developments the fanciful and fantastic elements of the 1 romantic ' school offered special opportunities to the imagination of the librettist, while the more recent Italian school again has offered scope for the invention of plots with swiftly moving dramatic action. Meanwhile Wagner had solved all difficulties for himself by writing his own texts, as did Charpentier and Borodin, and in two important cases Debussy (' Pelleas e t Melisande) ' and Strauss ( ' Salome ') have reverted to the setting of actual plays practically in their entirety. History has shown that the indispensable requirements for a successful opera libretto cannot be absolutely defined. Sometimes it appears that the musical expression is sufficient to outweigh dramatic and literary deficiences of the text, and we may predicate that real human interest in the central situations comes first in importance ; next, it must afford scope to the composer for musical illustration and expression of those moments. In fact the sway of music is such that it can easily compensate for the absence of literary or poetic style ; there are innumerable instances where it has been successfully left to the singer to simulate the delivery of true elevation of thought or passion, only suggested by the text in the crudest form. This, however, is ultimately a matter which concerns the composer alone, for we measure his inspiration by the result. Another example of the power of the music lies in the modern rejection of Wagner's doctrine that the period of an opera must necessarily be put back into legendary times. Many theoretic ideals are shattered by the colder iogic of practice, for, in opera, music can idealise almost everything it touches, and its truthfulnoss of expression or the reverse is not to be measured by comparison with actualities. M an y famo u s l ib r e t t i s t s will be fo u n d u n d e r th e i r own n am e s in th is D ic t io n a ry ; a t t e n t io n m a y be c al led to : R in u c c in i , th e F lo r e n t in e p oe t, whose t e x t s we re s e t b y P e r i , Caccini, M o n tev e rd i a n d Gag lian o ; F er ra r i , p o e t a n d c om p o s e r ; Z en o , 1668-1750, c o u r t p o e t in V ien n a a n d Venice, su p p l ied t e x t s for, am o n g s t o th e rs , C a ld a r a ; Me tastasio, whose w o rk e n jo y ed e n o rm o u s p o p u la r i ty , being s e t b y all th e le ading o p e ra comp o se rs of his t im e- Ha sse, Porpora, Piccinni, Paisiello, Gluck, Mozart, Caldara, etc., many texts, indeed, being set over and over again. Arne's ' Artaxerxes ' was a translation of Metastasio's text. In the foundation of French opera Perrin was associated with Cambert and Lully. The ' Armide ' of Quinault, who wrote for Lully, was later set by Gluck. Other French librettists to be mentioned are Sedaine (1719-97), librettist to Philidor, Monsigny and Gretry, and Favart (1710-92) (his ' Bastien et Bastienne ' was set in a German version by Mozart). Calzabigi (1714-95) was Gluck's collaborator in * Orfeo,' ' Alceste ' and ' Paride ed Elene.' Da P ont e wrote ' Nozze di Figaro,' ' Don Giovanni ' and ' Cosi fan tutte,' and S ch ik a ne d e r ' Die Zauberflote.' Weisse, 1726-1804, collaborated with Hiller in the foundation of the German Singspiel, and Kind wrote ' Der Freischutz ' for Weber. Bouilly was the author of ' Les Deux Joumees * and the original version of ' Fidelio.' The text of Cherubini's ' Anacreon ' was by Mendouze, and that of Spontini's ' La Vestale * was by Jouy (V. J. Etienne). In Italian opera of the 19th century the chief librettists were: R omani , associated with Bellini and Donizetti; Carmmarano, wrote ' Lucia ' and ' II Trovatore ' ; Piave, ' Rigoletto,' ' Traviata ' ; Ghislanzoni, ' Aida ' ; and B oito, ' La Gioconda,' ' Falstaff,' ' Otello ' and his own ' Nerone.' In French opera of the same period Sc r ib e wrote for Boieldieu ' Dame Blanche ' ; Auber, ' Fra Diavolo ' ; Verdi, ' Vepres siciUennes ' ; and Meyerbeer, ' L'Africaine ' and ' Robert le Diable.' He was associated with Deschamps in ' Les Huguenots ' and ' Le Prophete.' (See also Sain t - G e o rg e s .) Barbier and Carre wrote ' Faust ' and ' Mignon ' ; Meilhac was associated with Halevy in ' Carmen ' and with Gille in ' Manon ' ; Massenet was also supplied with texts by Gallet and H. Cain. The librettos of Puccini's most famous operas, ' La Boheme,' ' Tosca ' and 1 Madame Butterfly,' are by L. Illica and G. Giacosa. H. von Hofmannsthal wrote for Strauss ' Elektra,' ' Salome,' ' Der Rosenkavalier,' etc. Among English librettists there should be mentioned Nahum Tate, the author of ' Dido and Aeneas ' (Purcell), Bickerstaffe and Gay of the ballad opera period. J. R. P l anche wrote ' Oberon ' for Weber. Alfred B u n n wrote ' The Bohemian Girl,' J. Oxenford ' Lily of Killamey,' Fitzball 1 Maritana ' and H. F. Cho r l ey ' The Amber Witch,' etc. In a later period Mackenzio'3 ' Colomba ' and ' Troubadour ' had texts by F. H u e f f e r . Julian Sturgis wrote ' Ivanhoe ' (Sullivan), ' Nadeshda ' (Goring Thomas) and ' Much Ado about Nothing ' (Stanford). In light opera the outstanding names have been W. S. Gi(bert, Basil Hood and Sydney Grundy, the first of whom, through his masterly collaboration with Sul l ivan (q.v.), created a unique type. I t remains to add a few words about translations of libretti into English. This is a difficult matter for the translator, who has often failed in trying to satisfy all the claims of poetic diction, correct accentuation, correspondence between the salient, notes and words in a phrase, rhyme and literalness. I t is obvious that something has to be sacrificed, and it is a safe rule to sacrifice rhyme and literalness first. A carefully written paraphrase can be made to fit the case, and occasionally it is legitimate to make a slight alteration in the music itself, at any rate as regards note values in the vocal part. I t is a matter for satisfaction that the standard of translation into English has improved in recent years, for inferior work is unquestionably hampering to the English temperament, and hinders truth of expression in performance, besides annoying the hearer, and even tending to discourage the appreciation of opera as an art-form. The best work has been done in the translation of the Wagner operas ; there are now several good versions of the ' Ring,' notably that by Ernest N ewman. I t is, however, one thing to possess a good translation and quite another to get it into general use, owing to the unsettled conditions under which the performance of opera in English is conducted in this country. N. c . o.