"In the early 18th century the condition of opera was very 'low'". The accepted number of characters was six, three of each sex. There were three acts of a given number of verses based on Greek drama. The chorus stood motionless except for the leader, in a double row with the sexes separated and masked. The same libretti were used time and time again. The poets became as stilted as the composers. There were five types of melody whose sequence and distribution were regulated by rules, and not by dramatic requirements. Though varied in other ways, the songs consisted of two parts, the first repeated "de capo" after the second, notwithstanding the histronic result. The vocalist tyrannized over the performance, displaying no musical feeling, nothing but vocal agility. In England and Germany the singers sang their own language during the performance, for every thing except the formal arias, which were sung in Italian. Each act had to close with an elaborate finale, and each singer had to have an aria.

Sammartini in Milan gave prominence to string quartets. There was much stress laid on technical proficiency and arias. The dances became better than the vocal music, for the arias especially were monotonous and forced, and overloaded with ornament and contained practically no counterpoint. The overture, customarily in three parts, was separated from the opera itself. The arias were in bravura style with long and prolix ritornelli. The dramatic airs were absolutely spoiled by florishes.

Gluck freed the opera from many of these forms. He maintained that the function of the music was to support the poetry without interrupting action or disfiguring by superfluous ornament. The dramatic action was given more importance and the concerted pieces with stereotyped de capo were discarded. He was criticized for sacrificing music to drama, which would often have been better without it. This has also been said of Debussy's "Pelleas and Melisande." Gluck colored his music and avoided interrupting the actor in the warmth of the dialogue to wait for ritornello, flourishes and repetitions. He maintained that the overture should prepare specifically for the character of action and indication of the subject. Instruments should be employed in proportion to the degree of interest and passion. Above all he worked for simplicity; that opera must express life in aria and in recitative, and in similarity between the passion and the object called forth. His melody was supported by harmony and was varied in rythm. He strove for pictorial representation in his airs and accompanied his recitatives by figured bass and chords of the harpsichord, and employed several airs preceded by long instrumental solos. He changed and consolidated the structure of the opera on the verbal basis, and repressed the vanity and egotism of the singers. He galvanized the lazy languid orchestra into life and made the recitative play a more important part, making his opera dignified, overture elucidatory, accompaniment significant, and emphasized the coherent principle of unity.

In "Telemaco" Gluck imitated aspects of nature in several of the arias with greater unity of handling, truer dramatic expression, and continuous interest in the recitative. There are nine numbers following in dramatic sequence. He abandoned the symphony in three pieces making his overture lead into the opening aria. His two themes begin finely in contra-distinction but they degenerate into bravura style. Gluck studied literature and filled in the void for recitative so that the audience could-not play chess in between numbers.

"Orpheus" is lyrical and noticeable for the dramatic interest of the recitative, and the importance of the work given to the chorus. His duo-thematic treatment of the orchestra here is not successful. In his short orchestral prelude he breaks away from the spirit of the overture. The chorus takes up the broad sad theme. Orpheus cries, "Eurydice", twice, the third time he sings a note higher and stands against chords of diminished intervals, instead of blending with the chord of the minor third of the dominant, making a striking dramatic effect. The theme of the aria is echoed behind the scenes. In the accompanied recitative the orchestra has a share in producing the effect. In one aria when the sense of the words changes, the whole character of the music changes. Three fourth time, in the key of G, is used to depict the happiness of man. Where Cupid relates to Orpheus, an andante in three eighth time in the key of D is used.

Gluck has too many contrasts of slow and fast to be effective. His overtures and finales are weak, and he could not quite effect a compromise between the musical and the dramatic.

He improved the old antagonism between the aria and the recitative by giving the orchestra the function of adding some sort of color to the mere vocal padding. He insisted on acting, instead of mere singing by posturing sopranos and a chorus of wax figures. He insisted also on his music being sung as written. His bold stroke was uneven, but such a dramatic genius has never been surpassed.

In "Alceste" his overture assumed a new significance. It had no formal end but was broken into by the chorus. In "Armide" each character had music personally distinctive. "Iphigenie en Tauride" combined dramatic sincerity, superb use of recitative, natural and telling though simple choruses, throbbing height of passion, unification of parts of soloists, chorus and orchestra. He is termed a "creator of dramatic music". Orchestration was his specialty although he introduced it subservient to action. However, Gluck never employed trill passages or cadenzas, for he wanted to accentuate nature and strengthen declamation. His choruses are treated as "an additional acting character", and his recitative is true to the dramatic import. Rameau's and Lulli's operas were crabbed and rigid in comparison. Gluck alone gives each personage a style that is proper. The musicians who would not, or could not sing, except from the wings, were ignored by Gluck, and he refused the undramatic demands of the manager. In "Iphigenia en Tauris" the chorus works into a background which appropriately and dramatically supports the singer. The two tendencies in Gluck are, to neglect all sensuous aesthetic pleasure for attainment of dramatic intensity through declamation, and to realize his purpose through emotional pleasure, harmony of color, greater unity of scenes, the carrying out of one dramatic idea from the beginning to the end, making each individual part stronger.

Piccini was the innovator of the dramatic treatment of the duet and extended development of the finale. He was the first to turn choral masses to account on the stage. He used "Recitative instrumento" in pale of the ordinary "Recitative secco." Mozart enlarged on his ideas, for his command of the orchestra was unrivalled as a dramatic factor. Cimarosa placed a statue on the stage, with a pedestal in the orchestra, while Mozart placed the staue in the orchestra, using the work of the stage as the pedestal. Cimarosa uses the accompaniment for the support while Mozart intensifies the voice. Cimarosa was the first to introduce quartets and other concerted pieces in the midst of dramatic action, and not as an ornament at the end of the act, but he was outdistanced by Mozart. Before this, opera was merely a recitative, with a chorus at the end of each act, and then occasional airs were introduced, but not before the middle of the 18th century do we find trios, etc.

Beethoven and Weber followed Gluck. Beethoven gave to the orchestra the explanatory character of the chorus. He employs twenty phrases for a single character in "Fidelio". Weber used spoken dialogue and recitative sparingly but when neccessary composed with originality and dramatic vividness. He tried to construct drama by means of melody and failed. The first example of a grand orchestral prelude is written in six-fourth time to "Der Beberrscher der Geister." The overture to "Der Freischutz", by the use of leading themes, relates the entire story.

In the Italian and French school, "a la Sopontini" the orchestra lifted and balanced the words and the spirit of the orchestra reveals the innermost emotions of the dramatic personae. The Mythical manner is chosen, and a use of alliterative verse with a peculiar use of the orchestra as preparing, supporting, commenting upon, enforcing and recalling the various situations of the text.