Mozart's Cosi Fan Tutte came fairly late to Britain. It is Mozart at his most sublime, the music is haunting and beautiful, yet the story is simple.

Two young officers, Guglielmo and Ferrando, are in love with two sisters, Fiordiligi and Dorabella. A philosopher, Don Alfonso, wagers them that, if they were to go away, the two girls will soon love another.

The two officers say that would be impossible and the two sisters would remain faithful throughout.

To win the bet, Don Alfonso persuades the officers to pretend they have been called away to war and then return in disguise to test the sister's fidelity.

As so often with Mozart, the opera has a comic-serious duality. The division is not often clear as the sheer beauty of the music hits the listener at a deep, emotional level - far deeper than Lorenzo da Ponte's libretto warrants.

Right from the beginning of the overture, Mozart hits the right note of humour and great exquisite melody. Throughout the opera, it is the ensemble singing that leaps out.

In Whisper The Wind, the two sisters sing of the departure of their lovers so wistfully that the farcical elements of the story soon turn into a true tragedy.

The sisters' arias are a marvel of exploited despair, while those of the two men are the anchors to the story. The end result is a magnificently worked piece that does what Mozart does so well - tell us about our own humanity.

Nothing is known about the creation of Cosi except that it followed a successful revival of The Marriage Of Figaro in Vienna in 1789.

Its first run was interrupted by the death of Emperor Joseph II but there was a second run. Then, for much of the 19th-Century and the first part of the 20th, it was regarded immoral and frivolous and not worthy of Mozart's genius.

Scottish Opera brings its 1998 production to Brighton. This was a production considered controversial at its outset because of its young cast dressed as schoolboys and schoolgirls.

It is a modern, one-set production and has been described as "Mozart Meets Hollywood".

The emphasis is very much on the humour, making its sub-title The School For Lovers more apt than usual.