On his arrival every summer at Tanglewood, Andris Nelsons submits to a ritual round of interviews with the media […] He lets the music speak for him.

Near the mid-point of the season, the BSO’s music director returned for three programs in the first of his two weekends of concerts. Unusually, he took a microphone at his opening concert Friday night to welcome the audience, introduce the music and reminisce that the evening’s principal work, Mahler’s Ninth Symphony, was the one with which he had made his BSO debut in Carnegie Hall in 2011.

The last shall come first. The program consisted of Mozart’s Piano Concerto No. 25, his last in the genre, and Mahler’s last symphony. The evening was long; the Mahler symphony alone runs 80 minutes. In the end, it was heartbreaking.

The playing all night was broadly, richly responsive to the music and conductor. It had a wonderful transparency, illuminating even Mahler’s darkest places. Leonard Bernstein, a touchstone for Mahler performance, made the Ninth more obsessive, more extreme. Nelsons gave it an inexorable logic. There’s nothing like having the master in charge of his house.

The Ninth is the symphony Mahler composed when he knew he was dying of a heart infection. The performance came to Tanglewood well prepared from the repertoire from the BSO’s spring tour of Europe.

The orchestra turned sprawl into drama. Longing for life while confronting death, the playing raged and sighed, turned ugly and turned silken. The first movement, with its insistent two-note motif, was a premonition of disaster. The long final adagio, revolving around a five-note motif, delivered cataclysm that dissolved into lingering farewell and silence.

It was telling — and rare — that at the end Nelsons held the audience in rapt silence for a good 30 seconds before applause could begin.

The program opened with Jonathan Biss as an elegant soloist in the concerto, which Mozart wrote toward the end of his short life when acceptance in Vienna for his other music was flagging. The performance, marked by delicious give and take between soloist and orchestra, bathed the music in a mellow light.

On Saturday night, Augustin Hadelich went to the lonely heart of the Sibelius Violin Concerto as soloist.

In one of the most difficult concertos ever written, the German-born violinist gave no hint of the technical traps. Instead, with a dark, sometimes throaty tone, he made Sibelius’ isolation in the northern woods all but painful to endure. The whirlwind finale became a dance of death. The BSO accompaniment was tailored to fit […] Nelsons returns for concerts on Aug. 20 and 21. None too soon.”