From the fidgety stage mannerisms and puckish smile, he might have been mistaken for one of those bad-boy actors or a soccer star who never wanted to grow up. But he’s an English baritone — a 59-year-old one at that — and at his Philadelphia Chamber Music Society debut Friday night at the Perelman Theater, Simon Keenlyside never stopped moving.

He paced the stage. He extended his size by constantly choreographing his arms, stretching them out as a dancer does or stabbing the air for emphasis. Sometimes he seemed to be singing directly to an imaginary figure somewhere mid-stage. Keenlyside is very much a creature of the theater.

But even for listeners who want the meaning of lieder delivered in pure sound, Keenlyside did not disappoint. He keeps the best of musical company, from a partnership of equals with pianist Malcolm Martineau to an imaginatively conceived combination of repertoire that resonated from piece to piece.

And then there’s the voice itself, which does a beautiful job acting apart from the intrepid stage physicality. Keenlyside is, quite simply, one magnificent singer.

He brought a lovely specificity to the characterizations in Schubert, and held a terrific sense of atmosphere in Brahms. But truth be told, there was something about his way in the French repertoire in this recital that felt like his spiritual home. In Poulenc’s Le Travail du peintre (The Work of the Painter), the composer puts incredibly evocative sound to text by surrealist poet Paul Éluard. The use of vocal and pianistic color are just the beginning of the way Poulenc pulls music from the images of Picasso, Klee, and others. For Keenlyside it was about emotion. The last two lines of “Chagall” — about a face with moonlight lips that has never slept at night — was shaped by the singer with such meaning that they were an entire story in themselves.

Baritone Simon Keenlyside and pianist Malcolm Martineau at the Perelman Theater on Friday night.
Baritone Simon Keenlyside and pianist Malcolm Martineau at the Perelman Theater on Friday night.

He opened with a set of eight Schubert songs, all impressive in the way both he and Martineau took subtle cues from the texts. Has any brook flowed more gently than the one Martineau created for “Liebesbotschaft” from the Schwanengesang, D. 957? In Brahms, he was the muffled footsteps in “Uber die Heide” (“Over the heath”), and he provided the raging sea in “Verzagen” (“Despair”).

Similarly, Keenlyside’s great gift is the way he shades emotional intent by changing his sound, and he has an extensive palette. He unfurled all of the pride and majesty of a peacock in the opening movement of Ravel’s Histoires naturelles (Natural Histories): the colorless cry, the warmth of the sun, the humor of the strutting bird. In “The Kingfisher,” there were times when he put hundreds of years of cultivated operatic tradition into his voice, and moments when he used the plain, colloquial tone of a guy who just wanted to share a quick story.

Keenlyside got the core character of each composer, but each in a different way. In Brahms and Schubert, the music was studied and finely crafted. Somehow in Poulenc and Ravel, though, he delved deeper. He inhabited the music from the inside.