The first concrete instance of a deliberate embodiment of impressionistic method is to be found in the exquisite 'Prelude to the Afternoon of a Faun' (1882), founded on the poem by Mallarmé. Here Debussy succeeded admirably in translating the vague symbolism of the poem into music of languorous mood and ineffably delicate poetry. This brief piece, novel and striking in both harmonic and expressive idiom, marks a departure into a field of fertile consequence and far-reaching import both intrinsically and historically.
It was in the summer of 1892, also, that Debussy quite by chance came across Maeterlinck's play Pelléas et Mélisande. Both the intensely human elements in the drama and its sensitive symbolism made a strong appeal to Debussy's newly awakened æsthetic instincts and, after obtaining permission to utilize the play as an opera text, he at once set to work upon it. For ten years Debussy labored upon Pelléas with a patient striving to realize in music its humanitarian sentiment, its creative poetry and its tragedy. During these years of gradual distillation of thought he attained slowly but surely the inimitable style of his maturity. But in the meantime he composed also in various other fields.
Already the songs, Fêtes galantes (1892), on Verlaine's poems showed in their delicately impressionistic introspection that the 'Afternoon of a Faun' was no casual experiment. Similarly, the Proses Lyriques (1893), although unequal, exhibit clearly, especially in the songs De Rêve and De Grève, a formulation of the whole-tone idiom, which was later to become a characteristic feature of Debussy's style. A string quartet (also 1893) was, by virtue of its inevitable restriction, a momentary abandonment of the impressionistic ideal, but within these limitations Debussy achieved an astonishing individuality, charm of mood, and clearcut workmanship, particularly in the thoughtful, slow movement and the piquant scherzo. In 1898 he returned to the impressionistic vein with three Chansons de Bilitis from the like-named volume of poems by Pierre Louys. The naïveté, humor, and penetrating poetry of these lyrics were akin to the imaginative vein of the Fêtes galantes.
In the following year Debussy gave a larger affirmation of his impressionistic creed with the Nocturnes for orchestra entitled 'Clouds,' 'Festivals,' and 'Sirens' (the latter with a chorus of women's voices). These pieces, although avowedly programmistic, do not attempt realistic tone-painting, but aim rather to suggest impressionistic moods growing out of their titles. The slow procession of clouds, the dazzling intermingling of groups of revellers, the elusive seduction of imaginary sirens are pictured with an atmospheric verity that far transcends the possibilities of realistic standpoint. Musically the Nocturnes are distinguished by their intrinsic potency of expression, their basic formal coherence and logic of development, their concreteness of mood, and their picturesqueness of detail. The use of a chorus of women's voices, vocalizing without text, a feature already employed in 'Spring,' was not original to Debussy, for Berlioz had already employed it in his highly dramatic but little known Funeral March for the last scene of 'Hamlet' (1848). But Debussy's highly coloristic and ingenious application of the medium greatly enhances the pervasive poetry of this Nocturne, and transforms it into a virtual novelty. Not the least interesting harmonic consideration of this piece is the use, with some definite system, of the whole-tone scale, which Debussy later exploited so remarkably, and of which up to this time only transient suggestions had appeared.
During his long contemplative absorption in Pelléas Debussy had not entirely neglected composition for the piano. A Marche écossaise 'on a popular theme' ('The Earl of Ross's March') for four hands (1891, orchestrated in 1908) is piquant and vivacious without being particularly characteristic. A 'Little Suite' for the same combination (1894), if somewhat slight musically, is pleasing for its clarity and simple directness. In 1901, however, Debussy showed a far more definite originality, both pianistically and harmonically, in a set of three pieces entitled Pour le Piano, with the subtitles 'Prelude,' 'Sarabande' and 'Toccata.' If the prelude suggests something of the style of Bach, if the Sarabande is to a certain extent a modernization of the gravity of Rameau, and the toccata bears a resemblance in its fiery impulsiveness to Domenico Scarlatti, these pieces are none the less positively characteristic of Debussy in their fundamentals. The frank use of the whole-tone scale in the prelude, the harmonic boldness of the sarabande with its sequences of sevenths, and the ingenious piano figures in the toccata are the external evidences of a basically individual conception. If these pieces do not display the impressionism that is indigenous to the later Debussy, they represent a transition stage of far from negligible interest.
With the performances in 1902 of Pelléas et Mélisande at the Opéra Comique Debussy attained an immediate and definite renown. There was abundance of opposition, disparagement, and ill-natured criticism, but the work was too obviously significant to be downed by it. To begin with it was epoch-making in the annals of French dramatic art in that it marked a complete enfranchisement from the influence of Wagner. Debussy had been censured for saying that melody in the voice parts (that is, formal melody) was 'anti-dramatic,' but his by no means unmelodic recitative with its fastidious attention to finesse of declamation justified the restriction of the melodic element to the orchestra. If the dramatic style of Pelléas, in its economy of musical emphasis, was directly modelled upon Moussorgsky's Boris, the evolution of this idea in which the orchestra throughout, with the exception of a few climaxes, maintained a transparent delicacy of sonority, established a new conception of dramatic style as well as new resources in sensibility of timbre. Harmonically, Pelléas shows both a surprising unity (considering that it occupied Debussy for ten years at a transitional phase of his career) and a remarkable extension of devices scarcely more than hinted at in his earlier works. It is difficult to formulate these innovations briefly, but they may be grouped under three general headings. First, an æsthetic abrogation of certain conventional harmonic procedures; the free use of consecutive fifths and octaves, sequences of seventh chords (in which Fauré definitely anticipated Debussy), and of ninths. In these seemingly anarchistic over-rulings of tradition Debussy was guided by a sure and hyper-sensitive instinct. Second, the employment of modal harmonization, sometimes strict but more often free, with a singularly felicitous dramatic connotation. Third, the development of a logical manner founded on the whole-tone scale. Debussy cannot claim that he originated the whole-tone scale, since it was used by Dargomijsky in the third act of 'The Stone Guest' (1869), by various neo-Russians, notably Rimsky-Korsakoff, by Chabrier, Fauré, and d'Indy (in the second act of Fervaal); nevertheless he can be said to have made this idiom his own by his flexible and discriminating manipulation of its resources. Debussy does not employ the whole-tone scale as monotonously as is often supposed. On the contrary, one of the marked features of his harmonic style is its resourceful variety.
Debussy's use of motives constitutes the very antipodes of Wagner's somewhat cumbrous symphonic development of them. If at first Debussy's treatment seems too fluid and lacking in continuity, a closer study of the score (especially in the orchestral version) will reveal not only a flexible adaptation of motives to the dramatic situations, but a logical and constructive development often with considerable contrapuntal dexterity. Furthermore, a formal coherence is maintained without the artifices of symphonic development.
But the import of Pelléas does not consist merely in the historical or technical value of its innovating features, although this is patent. It resides primarily in the basic poignancy with which the music illustrates and reinforces the touching drama by Maeterlinck, as well as its intrinsic surpassing beauty and poetic thrall. It is because Debussy has characterized the innocent, gentle Mélisande, the ardent Pelléas, Golaud haggard with jealousy, the childlike carelessness of Yniold during a questioning of such import to his father, with such searching fidelity to the creations of the poet that we find music and drama in accord to an extent seldom witnessed in the history of opera. It is because Debussy has brought such freshness of musical invention and profound aptness of interpretation in such scenes as the discovery of Mélisande by Golaud, the questioning end of Act I, the animated scene between Pelléas and Mélisande in Act II, their long love scene in Act III, the dramatic duet at the end of Act IV, and the death scene of Mélisande in Act V, that this opera occupies a unique position. The characterization of the forest, of the subterranean vaults of the château, of the remorse of Golaud after his deed of vengeance, and the purifying majesty of death show Debussy as a poet and dramatist of indisputable mastery. Indeed, it is not too much to say that Pelléas et Mélisande occupies a position in modern French music akin to that of Tristan und Isolde in German dramatic literature.
After Pelléas, Debussy turned again to the impressionistic style in piano pieces and orchestral works of progressive evolution. With the 'Engravings' for piano (1903) containing 'Pagodas,' 'Evening in Grenada,' 'Gardens in the Rain,' he continued the impressionistic method of 'The Afternoon of a Faun' with an amplified harmonic and expressive idiom. 'Pagodas,' founded on the Cambodian scale, and the Spanish suggestions in 'Evening in Grenada' are characteristic instances of the French taste for exoticism; 'Gardens in the Rain' is founded upon an old French folk-song which Debussy used later in the orchestral Image, Rondes de Printemps. All three are markedly individual, and display the poetic insight of Debussy tempered by discretion. 'Masks' and 'The Joyous Isle' (both 1904) contain alike fantastic exuberance and an increasingly personal pianistic and harmonic style. The latter in particular contains a homogeneity of thematic development supposedly incompatible with an impressionistic method. Two sets of Images (1905 and 1907) make still greater demands upon the impressionistic capacity of the listener, sometimes at the expense of concrete musical inventiveness, but those entitled 'Reflections in the Water' and 'Goldfishes' offer no diminution of imaginative vitality. 'The Children's Corner' (1908), a collection of miniatures, are sketches of poetic appeal, though relatively slight. The final number, 'Golliwog's Cakewalk,' is a fascinating French version of ragtime style. Mr. André Caplet has orchestrated these pieces with sensitive taste. Two series of 'Preludes' (1911 and 1913) exhibit both the virtues and defects of Debussy's piano music. In some the piano is scarcely equal to the impressionistic demands made upon it, others touch the high-water mark of Debussy's versatile invention. In the first set, 'Veils,' 'The Wind in the Plain,' 'The Enveloped Cathedral' are felicitously impressionistic; the 'Sounds and Perfumes Turn in the Evening Air,' 'The Girl with Flaxen Hair' are lyrically atmospheric, while in 'Minstrels' is to be found another inimitably humorous transcription of ragtime idiom. In the second set, La Puerta del Vino is an imaginatively exotic Habañera; La terrasse des audiences des clair de lune is of rarefied emotional atmosphere; 'The Fairies are Exquisite Dancers' and Ondine are brilliant bits of delicate fancy; 'General Lavine—Eccentric' is another witty adaptation of rag-time in the Debussian manner. 'Fireworks,' a brilliantly impressionistic study ending with a distant refrain of the Marseillaise in a key other than that of the bass, approaches realism, a final climax, before the above-mentioned refrain, consisting of a double glissando on the black and white keys simultaneously. 'Fireworks' is also notable for a cadenza which is not in Debussy's harmonic style, and which closely resembles cadenzas characteristic of Maurice Ravel. But, with the historic precedent of Haydn in his old age learning of Mozart in orchestral procedure, one must not deny the same privilege to Debussy. This detail is not without its piquant side, because Ravel has been unjustly reproached for too many 'obligations' to Debussy.
In the meantime Debussy has published several sets of songs entitled to mention. A second collection of Fêtes galantes (1904) shows a slight falling off in spontaneity, but Le Faune is imaginative and felicitously inventive, and in the Colloque sentimental an ingenious quotation is made from an accompaniment figure of En Sourdine in the first collection, justifiable not only on account of the sentiments of the text in the second song, but for the reminiscent alteration of the original harmonies. A charming song, Le Jardin (presumably 1905), from a collection of settings by various French composers of poems by Paul Gravollet, having a delightful running accompaniment over a measured declamation of the text, must be regarded as one of Debussy's best. With some departure from his usual choice of texts, Debussy has successfully set three Ballades (1910) by François Villon, reproducing with uncommon picturesqueness the archaic flavor of the poem. The same year witnessed the publication of Le Promenoir des amants on poems by Tristan Lhermitte, whose delicate poetic style is more characteristic of his established individuality. Of the 'Three Poems by Mallarmé' (1913) one must admit an exquisite but somewhat tenuous musical sentiment, not entirely free from the 'polyharmonic' influence now current in Paris.