With Leonard Bernstein's 100th birthday about four months off (Aug. 25),  the Philadelphia Orchestra with music director Yannick Nézet-Séguin celebrated him by starting at the beginning: the 1942 Symphony No. 1 ("Jeremiah"), his first major work, and one whose performance history is still in a state of evolution.

Bernstein's later two symphonies are weighed down by his various preoccupations, whether with jazz (Symphony No. 2 "Age of Anxiety") or with God (Symphony No. 3 "Kaddish"). But the youthful "Jeremiah" is a more medium-weight study in disillusionment that Bernstein the conductor seemed not to accept as such. He gave it a Promethean force that felt inappropriately labored.

Nézet-Séguin was about expressive precision, right down to the quieter bass clarinet solos, with a bit of spaciousness a la Aaron Copland.  Among the many other benefits, the second movement's melodic metamorphosis was particularly magical. And in the final movement, mezzo-soprano Sasha Cooke did an effective slow burn with texts taken from the Lamentations of Jeremiah that was no less profound for being understated.

Best of all, the thematic chain reactions from one movement to the next -- found in so many later Bernstein works -- were apparent in ways that are often lost in the diverse musical geography that the piece explores.

With Bernstein on the brain, you had to notice how Nézet-Séguin's Schumann Symphony No. 2 was the polar opposite of the impetuous untidiness of Bernstein's performances of this composer. Nézet-Séguin won stellar reviews for his smaller-scale Deutsche Grammophon-label recordings with Chamber Orchestra of Europe that were swift and audaciously mercurial. Since then, he has adapted that approach for the more majestic Philadelphians.

But not so much on Friday:  At the end of the second movement, when Nézet-Séguin pushed pedal to the floor, the orchestra was right there with him without seeming to break a sweat. Of course, the orchestra's sound gave added muscle to emotional climaxes. So you had the best of two worlds and then some.

Pianist Radu Lupu left you wondering why his Mozart Piano Concerto No. 24 had to be so wan. Solo moments rang out with quiet profundity. But much else was so reticient that the performance seemed to have little to offer. Yes, he's age 71 -- but many master pianists are still at their best at that point.  At least the orchestra's accompaniment had a strong narrative that sometimes coaxed Lupu out of his shell.

The program is to be repeated at 8 p.m. Saturday at the Kimmel Center. Information: 215-893-1999 or www.philorch.org.