This choice in Edinburgh is a brave tribute to the composer in this anniversary year. Like Bernstein's Mass, heard earlier this week at the Proms, this work is not a Mass in the conventional sense, but a celebration of life from a humanist perspective; Delius uses texts from Nietzsche's Also Spach Zarathustra. This link gives notes on the work by Eric Fenby, amanuensis to the composer, who was a uniquely well placed commentator. There is also on the same page commentary by the conductor Sir Thomas Beecham, who was an early champion of Delius. Last night's concert also had the distinction of being the only performance in the anniversary year of this rarely performed work which calls for massive forces.

This opening concert of the Edinburgh International Festival saw the well-loved English music specialist Sir Andrew Davis, best known perhaps for his Proms conducting as Chief Conductor of the the BBC Symphony Orchestra, return to these shores but this time to Scotland with the RNSO. He also conducted the South Bank centre's tribute to Delius in January this year They were joined by an international line-up of soloists and with Edinburgh's very own Festival Chorus, marking the combination of celebrating home-grown talent and attracting world-class stars which is the hallmark of the Edinburgh Festival. Sir Andrew received a very warm welcome from a capacity audience, and maintained seemingly effortless control over the mass of performers involved, the stage as well as the hall being absolutely packed.

As a work is important, not only in demonstrating writing for large forces as well as the well-known smaller works, but in setting out Delius' personal philosophy: it is something of a 'Credo' and this makes its title of a 'mass' make more sense, it otherwise arguably being an oratorio about the Nietzschian hero Zarathustra, who has also inspired Strauss. Having rejected conventional Christian beliefs, Delius was very influenced by Nietzsche. It is a work which is 'larger than life' in all senses.

Written in France and inspired by German writings, in both musical and philosophical terms, possibly more than any other single work of his, it argues against viewing Delius as an 'English' composer and instead seeing him as European / international in his influences and identity. The content of the lyrics calls to mind perhaps most readily Beethoven's 'Ode to Joy', but the most obvious musical reference is to Mahler's 'Wunderhorn' influenced large-scale works.

It is not often one thinks this space may be on the small side, but the piece opened with an effect which I can only describe as a 'wall of sound', a joyous blast surging out. This forceful opening broadens out into first an introductory recitative for male voice, with musical accompaniment of a sparkling character, calling to mind a brook running through a forest; and then a 'dance scene' to which all soloists contribute in turn, together with chorus. These, arguably the highlights of the performance, both strongly recall the soundworld of Mahler.

There is then a sudden shattering of the sunny mood, as night falls on this scene, and the hero cries, 'Woe is me' and confronts his own mortality. Here the change of mood was perhaps gradual rather than sudden, not quite having the dramatic tension which would have drawn out the change of mood with immediacy. The melancholy became much more apparent only later in this fourth scene, when in contemplating impending death, Zarathustra is tortured by visions of a spider spinning its web around his corpse.

The second half - which is set on the mountains rather than in the forest - is slower, and more reflective. The first, third and fourth sections have opening instrumental interludes which precede the entry of voices. These are charming in themselves, but also work well to refresh the listener between the musical and philosophical intensity of the sung sections. They perhaps bring a sound more instantly recognisable as Delian, idyllic and lyrical.

As the piece progresses, the baritone's role becomes larger, as he represents Zarathustra, a figure who is arguably semi-autobiographical for Delius, the work becoming in the second half more and more a recitative for him and the orchestra with occasional interjections from the other soloists and support from the chorus. The mood and pace of the opening return in the final section, which gathers pace leading to the unison 'Alle Lust will aller Dinge Ewigkeit' and building further to a triumphant close which then slips, almost Berg-like into the infinite 'Ewigkeit' (endless day).

Hanno Muller-Brachmann, who had the advantage of singing in his first language, was capable as the artist / hero /superman. However it is all the more noticeable that having less airtime and in some ways a lesser part, tenor Robert Murray's singing stood out as clear and incisive and I would single him out for particular commendation. Mezzo-soprano Pamela Helen Stephen has a golden honeyed voice which is a delight to listen to. She was in an eye-catching dress of impressionist colours, referencing a Monet garden and appropriate to the themes of the music. The festival chorus and the orchestral players are to be commended for their stamina in this musical marathon.

Juliet Williams