You could spend a lifetime delving into all of Franz Liszt's roles as Western music's great change agent. Or you might simply have listened in Tuesday, as pianist Louis Lortie laid them bare before a Philadelphia Chamber Music Society audience. At the American Philosophical Society, with oils of Washington, Jefferson, and Franklin gazing down from the stage, Liszt rivaled the radical old patriots for conjuring a new world.

In our time, Wagner may be the most frequently referenced starting point of modern music; opera as a medium has an obvious edge. But listen to what kind of narrative ground Liszt covers in just the first minute or so of the Sonetto 123 del Petrarca: a delicate opening prevaricates (what key are we in?), the music trembles, then hesitates, and, after a pass at sweet liberation, the piece is ready to really start.

Listen everywhere, too, for dissonance, and Liszt's ease for slipping casually from one key center to another. Lortie's recital consisted of two of Liszt's three suites for piano, the Swiss and Italian sets from Années de pèlerinage (Years of Pilgrimage). In a collection of variously volcanic and spiritually questioning sections, Liszt takes a wrecking ball to traditional harmony. It is always startling to be reminded how early some of these works fall on the timeline of atonality, written, over time, starting just eight years after Schubert's death in 1828.

It is, in part, the impressive technique that piques the interest of pianists. As a Liszt champion, though, Lortie might bring something different to the discussion than his predecessors.

Technique these days is off the charts, and Lortie does nothing to bring attention to himself. The encore arrived like a benediction after fire and brimstone: the tuneful and reassuring rocking of Liszt's Gondoliera.

But you had to appreciate Lortie's conscious intent to use technique in the service of making points musical rather than athletic. Everything became portraiture: his ringing tone in the fanfares of the Chapelle de Guillaume Tell, the gorgeously delayed resolution and Tchaikovsky-like melancholy he brought to the Vallée d'Obermann (a piece so overwrought with Wagnerian desperation it almost seems the piano struggles to contain it).

The section that drew the encore, deservedly, was the Après une lecture de Dante: Fantasia quasi Sonata. Lortie was a keen-eyed guide through heaven and hell, reminding us that Liszt also invented the tone poem.

From the opening demonic tritone daggers, through intense moments of silence, clashing of good and evil, and eventually out into the brilliance, it left no doubt that Liszt had access to places closed to mere mortals. As does his ardent advocate.