Gustavo Dudamel conducts Mahler's Fifth and Sixth

In the summer of 1901, Mahler celebrated his 41st birthday and began his Fifth Symphony. For all that was new about his first four symphonies, they were nonetheless song-filled, poetically and spiritually inspired products of 19th century German Romanticism. Although Mahler's moods were many, dark tunnels still promised light at the end. With the Fifth, and more so with the agitated Sixth, Mahler took the hard-edged, modernist plunge into a future and fate unknowable.

On Thursday, the day Gustavo Dudamel celebrated his 31st birthday, his Mahler Project turned the troubling 20th century corner in an imaginative performance of the Fifth Symphony with the Simón Bolívar Symphony Orchestra of Venezuela in Walt Disney Concert Hall. The next night, Dudamel led the Los Angeles Philharmonic in a driving, riveting Sixth.

When Dudamel recorded the Fifth five years ago, he took a score with which many conductors have trouble finding a trajectory, pretty much on its contradictory, if exciting, face value. Now his confidence has grown to ask unanswerable questions.

A possible way to read this symphony is as the farewell to one age and a wary but game readiness for the next. In five movements and three parts, it begins with a funeral march, introduced by solo trumpet dirge, the battle lost, the battlefield a plain of sorrow. The slow Adagietto, famous as memorial music, was not originally meant to be played snail-slow but as a robust song of love. That leads to a cheerful, contrapuntal rondo, its role in the drama unclear.

Dudamel and his huge Bolivar band readily underscored Mahler's wildness and most extravagant emotions. But most telling was his Adagietto, which is scored for strings and harp. It was quite slow but redolent of tender romance not tragedy, with the Bolívar harpist even sprinkling a dash of salsa dust. The Rondo sneaked in no longer boisterous but slyly full of an expectation for music heading in new directions.

The Sixth heads into those new places but with a reputation for being unrelentingly grim (it is called the "Tragic"). In four movements, with no extra-musical program, it is Mahler's most traditional symphony. But Mahler merely needed a trustworthy vessel in which to contain his startling musical experiments.

On Friday Dudamel was not, as he was in the Fifth, fancy. But neither was he grim. He attacked the Sixth with a frank rhythmic intensity that presaged Stravinsky's "Rite of Spring," which premiered in 1913, a decade after Mahler begin the Sixth and two years after he died. Dudamel tapped the L.A. Phil's incomparable responsiveness for Mahlerian ferocity and ephemeral delicacy. The sound, whether needing booming bass or evanescent percussion, maintained extraordinary tactile immediacy.

Mahler may have had Armageddon in sight in the Sixth, but he knew the world's wonders, and the sheer vibrancy of the L.A. Phil's instrumental dabs of color made this performance practically -- and usually for the Sixth -- a celebration of life. Gorgeous lyricism sprang, seemingly out of nowhere. Cow bells rang invitingly from onstage and off, as if the lush mountainside beckoned.

The slow movement is even more beautiful than the Fifth's Adagietto. The maws open in the Finale, but with such colors as music had never known, and these obviously interested Dudamel as much as the hurtling rhythmic energy.