The Met Orchestra Performs Mahler at Carnegie Hall The Met Orchestra Peter Mattei singing Mahler's "Lieder Eines Fahrenden Gesellen" with this orchestra led by James Levine at Carnegie Hall. Setting a benchmark for "beauty" in a voice, as in anything, is naturally a highly subjective endeavor. A sound one listener may consider distinctive may prove grating to another. Even some of the most beloved singers, like Maria Callas, had their detractors. But if a benchmark can be established, Peter Mattei surely has one of the most beautiful voices of any living singer - a mellifluous, lustrous baritone with no rough edges or imperfections. His moving performance of Mahler's "Lieder Eines Fahrenden Gesellen" ("Songs of a Wayfarer") with James Levine and the Met Orchestra on Sunday afternoon at Carnegie Hall reinforced that impression. That youthful song cycle, written before Mahler's symphonies and other large pieces, depicts the emotions of an abandoned lover. Mahler, who was inspired by the German folk poetry collection "Des Knaben Wunderhorn" when he wrote his own texts for the work, composed the cycle while infatuated with the soprano Johanna Richter. Mr. Mattei, a tall, charismatic and graceful stage presence, imbued the songs with myriad shadings and details, conveying an aching vulnerability in the opening song, which depicts the protagonist's sadness as he imagines his beloved's wedding to another. He sang with elegant phrasing throughout, as in the poignantly shaped line "Ah mein Leide" ("About my sorrow") that concludes the first song. The contrasts between sections were vivid, with Mr. Mattei rendering the dramatic third song with heartfelt conviction and singing with gentle radiance in the resigned final section. Mr. Levine and the orchestra accompanied him with equally revelatory playing, the swirling orchestral colors in the third section a potent counterpart to Mr. Mattei's despairing portrayal of the heartsick young man. After intermission came Mahler's Symphony No. 7, which lasts well over an hour and is scored for vast forces including trademark Mahlerian touches like cowbells. The sprawling symphony unfolds over five movements and was inspired by a verse by the German Romantic poet Joseph von Eichendorff - "Sleeps a song in things abounding, ever dreaming to be heard. All Earth's music starts resounding, if you find the magic word" - and the sound of lapping oars Mahler heard during a boat ride in Austria. The outer movements were the most convincing in this performance, with polished brass playing and an urgency that rendered the first section particularly vivid. An edge-of-your-seat excitement enhanced the tumultuous finale, which unfolded in a blaze of orchestral color. The meandering middle movements proved less effective, although Mr. Levine illuminated plenty of details, as in the atmospheric Nachtmusik I, which the composer compared to Rembrandt's painting "The Night Watch."