The idea of the "re pastore" or shepherd king can be traced back to the biblical figure of King David and was long an integral part of the western myth of kingship. The mark of such a ruler's legitimacy lay; in part, in the fact that he was chosen by a superior power, but it also stemmed from his consciousness, as one of the elect, of his responsibility towards the people placed in his charge. His adversary was traditionally a tyrant who, in his quest for absolute control, arrogates power to himself and rnisuses it for his own dcspotic ends This contrast between just and unjust claims to power is one of the hasic themes of opera seria, a genre that originated in the l7th century and which. in terms of hoth form and content, proved particularly well suited to portraying not only idealised power and grandeur but also the virtues that were believed to distinguish a monarch above all others.
Opera seria evolved against a courtly background and soon came to mirror courtly existence. Just as life at court was determined by endless ceremony, so opera camo to be dominated by a stereotypical dramaturgy that prescribed the relationships between the characters and the sequence of musical forms. All the features of a courtly festivity were faithfully preserved even when the performance took place in a public theatre. Themes and staging were always closely hound up with courtly ceremony, hence, presumably, many of the difficulties that arise when these works are staged today. The themes on which opera seria drew were hased on a pre-existing, socially inviolate system of values that conditioned the responses of all the characters and determined all their actions. Plots were generally borrowed from classical myth and history, with the result that the characters acquired a significance that was not so much individual as illustrative and allegorical. Situations and emotions were highly stereotyped and thus part of a symbolic. unnersally valid transcendental reality.
Initially; the heroic action's rigid framework was broken down by the introduction of comic characters and scenes, but this all changed following attempts to reform the genre by poem such as Apostolo Zeno and Pietro Metastasio, who sought to bring it closer to classical drama, with its insistence on unity of action. The number of roles was reduced and the intrigue derived from the conflicting interests of a first and second couple, To these were added a primo tenore, who was generally a ruler invested with positive or negative features and one or two confidenti, subsidiary figures in whom the main characters could confide and who helped the action along. The earlier range of musical forms was likewise curtailed, with choruses and accompanied recitatives reduced to a minimum, and duets or longer ensembles generally sanctioned only at the ends of acts. In essence, the action unfolded within a fixed framework of secco recitatnes and arias. The recitatives carried the action forward, whereas the arias - mostly placed at the end of a scene - interrupted it, while none the less fulfilling an essential dramaturgical function by portraying the characters' state of mind and their inner reaction to the foregoing course of events.

Metastasio's libretto for Il re pastore caught the spirit of the age, with its Enlightened, Rousseauvian predilection for the virtues of a simple life - virtues that were inevitably much idealised and treated as part of a pastoral idyll by beyng reworked in a playful Rococo spirit. In the process, the Italian poet picked up the tradition of the old pastoral drama from which opera had once developed. Against this Arcadian background, it was not so much the heroic and historicising intrigue that was central to the plot as the idea of reforming and humanising an ossified social order through the virtues of the heart.
For Metastasio, the complexities of the plot were not the result of a clash of noble and tyrannical forces, as was normally the case in opera seria. Rather, they sprang from misunderstandings that result when two different worlds and ways of thinking are brought into conflict. Alessandro embodies the intellectually ordered sense of vocation typical of western man. He sees it as his duty to restore a legitimate order that has been overturned, while giving no thought to the individuality of those affected. His plans founder on what, for him, is the incomprehensible world of ideas of the Asiatic characters, for whom the claims of the heart are more pressing than those of any superimposed order. As a result, the central character in the drama is not the hero Alessandro but the sensitive shepherd Aminta, who is, of course, none other than the unrecognised but legitimate heir to the throne.
Commissioned by Maria Theresa in 1751, the libretto was first set by the court composer Giuseppe Bonne, but, like all Metastasio's libretti, it was soon taken up throughout the rest of Europe, with the most famous composers of the day, including Hasse, Gluck, Sarti, Piccinni and Galuppi, all writing operas based upon it and invariably altering and adapting it to suit local conditions. For a visit to Venice by the Emperor Joseph II in 1769, for example, Galuppi revised his setting of 1762 and prepared a two-act version in the form of a serenata, a type of musical homage of a kind that win hugely popular at that time at the Viennese court.
Mozart, too, had recourse to a two-act version of  the libretto, in his case, one that had been devised for a performance in Munich in 1774, with music bv Pietro Alessandro Guglielmi. Mozart was in Munich superintending the première of his La finta giardiniera, which took place in the city on 13 January l775, when he received a commission from his Salzburg employer, Archbishop Hieronymus Colloredo, to write a serenata to celebrate a visit to Salzburg, in the April of that year, by the Archduke Maximilian Franz. At the same time the Salzburg court composer Domenico Fischietti, was commissioned to set another of Metastasio's texts, Gli orti esperidi. Each work was scored for five vocal soloists, namely, a soprano cstrato, two sopranos and two tenors. Two leading artists from the Munich Court Opem were engaged for the occasion: the castrato Tommaso Consoli and the flautist Johann Baptist Becke. The rest of the cast was made up of members of the Salzburg Hofkapelle. Mozart began work on the score at the beginning of March, shortly after his return from Munich. He did not stick exclusively to the Munich libretto, but on several occasions referred back to Metastasio's original. He also used a revised version of a number of other pnssuges, revisions that are believed to he the work of the prince-archbishop's chaplain, Giambattista Varesco, and that include Aminta's aria. "Aer tranquillo", and the final chorus, "Viva l'invitto duce", where the original would no doubt have been too short to provide a suitable homage for the visiting archduke.
We know little about the first performance of Il re pastore, which took place on 23 April 1775 as part of a programme of festivities extending over three evenings. All we can say for certain is that Mozart used parts of the score for other compositions and that individual arias were later performed in concert. In its entirety, the work was not revived until the 20th century, initially in a concert performance to mark the composer's sesquicentenary.

One of the most basic ingredients in Mozart's setting of the text is his use of irony, an irony based on the misunderstandings brought about by the clash between Alessandro's obsession with political order and the emotional nature of the Sidonian people on whom he attempts to impose a state of happiness. Alessandro is incapable of understanding their mentality, a state of affairs that all too often makes his decisions seem risible, not least because he himself never notices that everyone else is dissatisfied with them. Mozart does full justice to this inherently comic situation by creating two musical worlds for his characters to inhabit - two worlds that tire divided from one another by a barrier of incomprehension. The Arcadian world is characterised by music traditionally associated with peasants and shepherds and by its varied depiction of Nature, with the sound of flutes, for example, evoking a pastoral mood. Aminta's entrance aria ("Indendo amico rio") develops directly out of the overture and turns into a dialogue with the orchestra, which answers him to the strains of the rnurmuring brook with which he is comrnuning. The first amusing contrast with this mood of tranquil contemplation comes with Elisa's entrance: although a descendant of King Cadmus and hence of royal rank, she looks forward to leading a simple life with her lover, but this idea is exposed as an unrealistic pastoral idyll in her lively and charming aria, "Alla selva, al prato", with its accompagnato interpolations and boorishly rustic dance motifs in the orchestra. Here, too, there is the potential for misunderstanding: Aminta’s real situation is different from Elisa's mistaken conception of it, but love bridges the gulf between appearance and reality.
The very first scene between Alessandro and Aminta reveals the absence of any common ground in their attempts at mutual understanding. Although Aminta assures Alessandro that he has no interest in the grandeur and pomp associated with the world of heroes, Alessandro sees only virtuous modesty in that assurance.
For the present recording, the later ("B") version of the recitativo accompagnato, "Ditelo voi pastori", has been preferred to its earlier version, in order for it to serie as an introduction to the aria. "Aer tranquillo": Aminta invites the shepherds to share in his happiness and praises the joys of a rural existence, the carefree freedorns of which find apt expression in the aria's Allegro aperto. The minuet-like middle section depicts the contrast of life at court, which Aminta formally reject in the aria’s concluding da capo. Alessandro's recitative reveals him as no more than a simple army commander wanting to impose order on the world by first destroying it. The shepherds' irenic ideal is ironically contrasted with the "hero's" warlike outlook. With its accompanying trumpets and timpani, Alessandro's simile aria, "Si spande al sole in faccia", gives the hero ample opportunity to indulge in pompous attitudinising. Thunder and lightning symbolise the purging storm of war that he intends to visit on the world. Forte upheats on trumpets and horns and elaborate coloratura writing suggest a surfert of activity that turns into complacency in the aria's slow middle section. Meanwhile, the orchestral writing reveals that, with his blatant obsession with order, Alessandro is incapable of takitrg account of his antagonists' more peaceful rnentality.
The second couple, Agenore and Tamiri, are very much part of the courtly world. Agenore is a contradictory character, involved in several conspiracies but devoted to Tamiri, the refugee daughter of the tyrant Straton, a state of affairs made clear in his ravishingly tender aria. “Per me rispondete", which is cast in the form of a minuet. Tamiri's response, "Di tante sue procelle", describes her resultant happiness, which fills her with a new-found sense of liberation after all the torments and tribulations that she has suffered.
With the final scene of the opening act comes a dramatic increase in tension. Hating discovered his true identity, Aminta decides to embrace his destiny and in an accompanied recitative offers dramatic evidence of the contradictory emotions triggered by this decision both in himself and in Elisa. The orchestra conjures up their doubts and secret fears, while Elisa herself speaks of her joy. The final duet, “Vanne a regnar ben mio", finds Aminta confident and resolute, Elisa lovingly resigned and apprehensive. The C-section, in the form of a gavotte, sweeps aside all vague premonitions with its apparent ioy and faith in the future.
In the opening recitative of Act Two, Agenore reveals himself as a pompously self-important, fawning courtier in his dealings with Elisa. The scene is presumably intended as an ironical gloss on the sort of court ceremonial that admits of no natural reactions. With its numerous accompagnato passages, Elisa's aria, "Barbaro! oh Dio", constitutes a dramatic character sketch, as her emotions veer between disillusionment, anger and despair. Naïvely self-satisfied as ever, alessandro now looks for a further victim for his mania for imposing order on others: Tamiri is to marry Aminta. Unwittingly he plunges the second couple into a state of turmoil. With its carefree F major tonality, his aria, "Se vincendo vi rendo felici", reveals the full extent of his error. The contrast between the reality of the situation and Alessandro's superficial complacency can be regarded onsly as an expression of supreme irony: the exalted "hero" is revealed as a blind and uncomprehending fool. Aminta's aria, "L'amerò, sarò costante", is one of Mozart's most affecting expressions of love and, as such, the high point of the work. Cast in the form of a rondo, it is scored for somewhat unusual forces (flutes, english horns, bassoons, horns, solo violin and muted strings) that lend it an intimacy and, at the same time, a very real transparency of texture. Once again, the world of Arcadia is not far away. The rondo form is especially well suited to the subject matter, with its themes of eternal fidelity and heartfelt love. Already inwardly resolved to renounce the throne, Aminta is naturally thinking of Elisa at this point. although the conversation has in fact been about Tamiri. Yet, thanks to Mozart's incomparable ability to suggest several different layers of meaning at once, Tamiri, too, is involved here, since Agenore subconsciously transfers Aminta's confession of love to his own feelings for Straton's daughter: for him, Aminta can be referring only to Tamiri. As a result og this ambivalence, the aria acquires a particular aura of secrecy and mystery.
The shepherd Aminta places the claims of the heart above those of the throne, but for the courtier Agenore, the priorities are reversed: although he loves Tamiri, he believes it incumbent him to renounce her for dynastic reasons. In her A major aria, "Se tu di me fai dono", she confronts him with his inconsistent and wealdy passive attitude, which merely serves to intensify his anguish at the prospect of losing the woman he loves. He gives vent to his despair in a highly dramatic and agitated aria, "Sol può dir", the inner restlessness of wich is signalled by Mozart's imaginative writing for the woodwinds. The contrast between Agenore's vehement Allegro and Alessandro's following bravura aria in C major, "Voi che fausti ognor donate" (again, of course, with timpani and trumpets), points up the full extent of the latter's blindness: he sees only superficial greatness and is blind to the feelings of others, even when he believes he is making them happy. In the face of harsh reality, his attitude is little less than farcical. Even when those whom he has tried to make happy open his eyes for him and spurn his gifts, he refuses to change his outlook. Unbidden, he makes both couples rulers, since he is incapable of conceiving of such virtue without an empire to rule. The obligatory scene of homage, "Viva l'invitto duce", demonstrates Mozart's subversive irony in particularly striking fashion: although the act of homage is directed on a superficial level at Alessandro - and hence, of course, at the archducal guest of honour -, the fêted figure is really Cupid who, as love's agent, proves the ultimate victor.
It may be said in conclusion that although Mozart retained the formal model of opera seria in all its essential characteristics, he also gives it a new significance by dint of his use of irony and ability to express contradictory emotions through the ambivalence of his musical language, therehy investing Il re pastore with a validity far beyond that of the circumstances that first produced it.