Il Re Pastore, Linbury, ROH, London

That some of these arrows have or will find their targets is the central metaphor of the evening, and it's one that sits well with Mozart's score, delicately balanced as it is between the dulcet woodwinds of pastoral innocence and the martial brass of state. The contradiction is right there in the title - "The Shepherd King" - and is the heart of the drama. What price power?

Lloyd Davies has a good eye for visual metaphor - as he so successfully demonstrated in his Linbury staging of Britten's The Rape of Lucretia. His single-set design for Il re pastore presents us with a physical golden framework in which the drama unfolds according to 18th-century conventions. But that framework is already breaking down. Mozart is bending the rules of the game. And success in the game - like chess (which is another of Lloyd Davies' metaphors) - is all down to strategy.

And so, the tension between freedom and authority is kept hanging in the balance here. The natural and man-made worlds collide. A life-giving stream runs through exterior and interior scenes. Verdant foliage adorns the rooms of state. But will the humble shepherd become king? Will he sacrifice freedom - and even perhaps his one true love - to serve his people?

Mozart leaves us in no doubt as to what that freedom means to him. He exults in it. And a predominantly fresh young cast, working in close accord with the unvarnished immediacy of period instruments - the English Baroque Soloists - gave the evening an engaging honesty. Edward Gardner, ENO's newly appointed music director, conducted the proceedings with self-evident enthusiasm and style, maintaining the dramatic imperative through Mozart's succession of well-made arias and recitatives.

These arias - and one notable love duet - full of seductive chromatic yearnings, are more and more the shape of Mozart to come, but in one astonishing flash of genius, right at the moment where it matters most, Mozart has our shepherd hero Aminta convey to us the dictates of his loving heart in an aria of surpassing beauty. Katie Van Kooten sang it with rapt sincerity, the voice entwining with obbligato violin to achieve a transparency and truth worthy of comparison with Mozart's finest work.

The object of all that desire, Elisa, was sung by Ana James, whose expressive way with the coloratura was always meaningful. Indeed, it was a credit to each and every one of this cast that sense always came before show - that they sang on the interest more than the capital. Robert Murray certainly flung himself into Agenor's frustrations, while Anna Leese's Tamiri, though lacking colour in the middle and lower reaches of the voice, certainly conveyed imperiousness. As the unconquered hero Alessandro, Peter Bronder tellingly exploited the vanity of his pyrotechnics, something that Lloyd Davies underlined in a mock-heroic tableau of amusing banality.

At the close of Il re pastore, Mozart glimpses his future in an ensemble of amazing individuality. The Age of Enlightenment is suddenly upon us, and Alessandro's soldiers shed their greatcoats and masks - the uniformity of the past - and become living, breathing individuals. That, of course, would be Mozart's enduring legacy, too.

To 22 April (020-7304 4000)