Mozart's Requiem and Sibelius's Fourth Symphony were both written when their respective composers were staring death in the face, and each examines what Sibelius called "quest in the infinite recesses of the soul".

The Requiem is inseparable from the myth that surrounds it. The thought of Mozart on his sickbed, struggling up to the moment of death to complete the score, is one of the haunting images of western culture and we have come to regard the work as among the greatest expressions of man's confrontation with mortality. Sibelius, meanwhile, wrote his Fourth Symphony after undergoing surgery for cancer. The operation was successful, though for years he lived in fear of a relapse.

For his second concert with the London Symphony Orchestra, Franz Welser-Möst performed both works together, though what promised to be a harrowing evening to some extent misfired, largely due to his wayward approach to Sibelius. Welser-Möst sees the Fourth as essentially post-Romantic and expansive rather than taut and concise. He plays up the debt to Wagner, with deep strings echoing the Act 3 prelude of Tristan und Isolde and brass chorales firmly reminding us of Parsifal. This is insightful - both Tristan and Parsifal deal with the decay of the body, which Sibelius feared - but the dominant tone is one of nostalgia rather than dread and the Symphony's emotional range is inevitably blunted.

The Mozart was more successful, grave in its beauty, and fearful in its contemplation of what may await the human soul in the afterlife. Welser-Möst used the standard completion by Mozart's pupil Süssmayer, pointing up the disparity between Mozart's deep spirituality and Süssmayer's more operatic approach. He also added the Ave Verum as an appendix, ending the evening on a note of genuine consolation. The uneven quartet of soloists was dominated by Sally Matthews's seraphic, rapturous soprano. The LSO Chorus sang with an acute sense of drama, though its large numbers meant that some of Mozart's polyphony was occasionally blurred.