NOTHING brings a listener closer to the true interpretation of a musical work than having the composer conducts it himself.
English composer Sir Peter Maxwell Davies was on hand in Boston Monday night to conduct two of his pieces: the world premiere of ''The Beltane Fire'' and a 1988 trumpet concerto. Davies led the highly regarded BBC Philharmonic, which is nearing the end of a 20-city United States tour. The partnership between Davies, whose name consistently appears on lists of the top 20 living composers, and the orchestra is a longstanding one. He has recorded at least seven albums with the BBC Philharmonic, and a genuine rapport seems to exist between the congenial, enthusiastic composer and musicians.
The presentation of new work is a welcome event because in today's classical-music environment, it represents a triumph of energy, enterprise, and financing over dwindling support and funds. ''The Beltane Fire'' is even more triumphant because it is a modern composition that audiences, who may turn up their noses at contemporary music, will enjoy.
Davies grew up in Manchester, England, but now lives on a small farm on the northern tip of Scotland, in the Orkney Islands. This location has inspired much of his recent work, especially ''The Beltane Fire,'' which has interludes of traditional Celtic music tucked into it. Davies also invests the composition with the drama of storms pounding the Scottish coast, and of witchcraft.
This is not to say that the music is easy listening. Davies is a product of 20th-century musical ideas, and his work contains a strong dose of dissonance and complexity. But to this listener, Davies is more approachable here than Philip Glass or John Adams, to name two of his contemporaries. And Davies's strong sense of place -- his Orkney connection -- ties the dissonance to the wild coast and dark Celtic legends of his home. Because of this, the clashing notes seem more natural and less like an intellectual or tonal exercise.
In a charming introduction from the podium, Davies, a short man with small, quick movements like a bird, set the stage for his piece. He explained that in the 1600s, Orkney was under the control of newly appointed Protestant clergy, who wanted to stamp out pagan rituals and dance, which had been tolerated by the Roman Catholic Church previously.
''The Beltane Fire'' (which is a ritual fire ceremony) concerns the tensions between ''spiritual values and more earthly ones,'' Davies said. He compared the plight of suspected Orkney witches to that Salem, Mass., witches. ''But,'' he told the audience, ''why not make up your own story?''
The humble composer's comment liberated listeners and gave room to their imaginations. In passages, one could hear ominous tiptoeing of the strings, as if the villagers were slipping off to forbidden ceremonies. Other sounds included otherworldly rills shaped by shimmering bells and harp.
A wind-swept landscape appeared in the mind's eye, full of glowering skies and turbulent seas. Timpani and cymbals crashed, drums thudded, and brass sounded. Davies relishes percussive noises, and he uses them to great advantage in ''The Beltane Fire,'' including at one point a rattling sound achieved by crumpling what looked like big pieces of cellophane.
To contrast with this frenzy, Davies inserts Celtic melodies played by a trio of musicians on traditional instruments. In an inspired touch, the first violinist echoes the Celtic melody in a quiet but profound solo. Finally a bell is rung sternly, as if calling the dancers and mirthmakers to disperse, and the church reasserts its authority.
By the conclusion of ''The Beltane Fire,'' the composer was limp with his exertions on the podium. Those in the audience were equally exhausted, but exalted. It is hard to imagine a more effective and dramatic piece of contemporary music.
On the same program, brought to town by of the Bank of Boston Celebrity Series, was an esoteric Davies piece, ''Trumpet Concerto,'' performed by Hakan Hardenberger, who brought polish and command to the difficult music. Under principal conductor Yan Pascal Tortelier, the orchestra also played Four Sea Interludes from the Benjamin Britten opera ''Peter Grimes,'' and ''La Mer'' by Claude Debussy. It was a night that belonged to the sea.
* The BBC Philharmonic tour continues with three separate New York-area concerts tonight through Sunday; in Wilmington, Del. on April 11; and in Fairfax, Va., on April 12. (Davies conducts at all but the Wilmington concert.)