Copyist manuscript partbook of Lully's opera Isis (1677) with entries from other works dating up to ca. 1710 added. 164 pp, all lined with six musical staves in the same size and style. In ink throughout. Title to front pastedown: "ISIS Tragedie en Musique par M De Lully Intandant de la musique du Roy / Basse / GVERIN". Inscription to back pastedown: "M. Chevallier." Boards and spine heavily rubbed and chipping, but binding intact. Oblong octavo. 10 x 7.75 inches (26 x 19.5 cm).

Fol. 1–40: Isis, partbook of baritone/bass parts of the opera: roles of Hierax (baritone, notated in F3 clef), Jupiter (bass, notated in F4 clef), Argus (baritone, notated in F3 clef), Pan (bass, notated in F4 clef) and choral bass parts (notated in F4 clef). In Act 3, Scenes 2, 3 and 7, Hierax and Argus sing polyphonically, notated on 2 staves. Otherwise, the notation is on one staff and strictly monophonic, without accompaniment. Long rests in duets are written out, without cue notes. Beginnings of airs and other set pieces are indicated; occasional stage directions. All scenes without bass parts are omitted. Act 2, Scene 3, which would include Jupiter, is also omitted. Except for this last omission, the present manuscript seems to be a faithful copy of the printed Basse partbook (Paris: Ballard, 1677). Slight departures from full score at the Bibliothèque nationale de France in Paris. Penned in a bold, clear hand throughout. Beginning lacking (leaves removed); music begins only in the middle of Act 1, Scene 2, at [Hierax] "...tendre et credule." Further leaves removed between fol. 33 (Act 4, Scene 5) and fol. 34 (Act 5, Scene 2).

Further entries in a variety of hands, some possibly much later, all with figured "Basse continue" (continuo) line and mostly for soprano voice (notated in C1, G1 and G2 clefs):

Fol. 41v-42r: Roland, opera (1685) by Lully, prologue, beginning of Demogorgon's aria (breaks off after 27 measures), for bass.

Fol. 42v-52v: Didon, opera (1693) by Henri Desmarets (1661–1741), excerpts: Act 3, Scene 5, Air of Anne, "Il faut mourir", etc.

Fol. 53: Music theory, "rules for transposition."

Fol. 54r–56r: "Quand je te dis de répondre à ma flame", duet for soprano and bass, ascribed to "Monsieur Vidal" in the anthology Recueil d'air sérieux et à boire, de différents autheurs, pour le mois de juillet de l'année 1707 (Amsterdam: Estienne Roger), p. 165.

Followed by various Italian arias, all unidentified.

Fol. 62v-65v: "Paratum cor meum", motet (published 1710) by André Campra (1660–1744), end lacking (at least two leaves removed).

Fol. 66r/v: Fragment of Italian aria, unidentified.

Fol. 66v-67r: Fragment of Tantum ergo, unidentified.

Fol. 67v-68r: French air, "Au milieu d'un repas", unidentified.

Fol. 68v-69r: Blank staves.

Fol. 69v-70r: Air sirieux [sic]—Chaconne "Pour viure[?] soubles lois de l'amiable..."; unidentified.

Fol. 70v-71r: Blank staves.

Fol. 71v-72r: French air "Le verre[?] en main il pretend me dedire..."; unidentified.

Fol. 72v: Fragment of French air, unidentified.

Fol. 73r: Blank staves.

Fol. 73v-74r: "Suite [i.e. continuation] du Carnaua [sic] der Venise", Le Carnaval de Venise, opera by Campra (1699), Act 1, scene 1.

Fol. 74v-75r: "Flore de l'opera datis [sic]", Atys, opera by Lully (1676), excerpt from prologue.

Fol. 75v: Music theory sketches.

Fol. 76r: Blank staves.

Fol. 76v-79v: Duet between Doris and Sengaride [sic; Sangaride], "Quel mal vous fait l'amour," from Atys, opera by Lully, Act 1, scene 4.

Fol. 80r-82v: Excerpt (beginning lacking) from Le Carnaval de Venise, opera by Campra, Act 1, scene 1.

Musical sketches, notated upside down, to fol. 80–82.

Isis was first performed at the Château de Saint-Germain-en-Laye in January of 1677 before a series of public performances at the Théâtre du Palais-Royal in August of the same year. The opera was revived in 1704, 1718 and 1732. The partbook's inscription with the ownership signature "Guerin" raises the highly intriguing possibility that the partbook was prepared for or belonged to the actor-singer Isaac-François Guérin d'Estriché (1636-1728). He made his debut at the Théâtre du Marais in 1672 and ended up at the Hôtel Guénégaud when the troops merged; from March to October 1675, he participated in the performances of "Circe" by M.A. Charpentier, at the Hôtel Guénégaud; he bore both his father's and his mother's name; it is therefore the same person that Charpentier designates by "Des Triches" or by "Guérin" in the ms. of "Circe". In 1677, he married Armande Béjart, the widow of Molière, and who later headed the Comédie-Française.

Lully wrote one tragédie en musique almost every year between 1673 and his death in 1687, most to verse dramas by Philippe Quinault. Unlike Italian opera of the day, which was rapidly moving toward opera seria with its alternating recitative and da capo airs, in Lully's operas the focus was on drama, expressed by a variety of vocal forms: monologs, airs for two or three voices, rondeaux and French-style da capo airs where the chorus alternates with singers, sung dances, and vaudeville songs for a few secondary characters. The intrigue of the plot culminated in a vast tableau, for example, the sleep scene in Atys, the village wedding in Roland, or the funeral in Alceste. Soloists, chorus and dancers participated in this display, producing astonishing effects thanks to machinery. The earliest operas were performed at the indoor Bel Air tennis court (on the grounds of the Luxembourg Palace) that Lully had converted into a theater. The first performance of later operas either took place at court, or in the theater at the Palais-Royal, which had been made available to Lully's Academy. Once premiered at court, operas were performed for the public at the Palais-Royal.