While some of us might stick a candle in our oatmeal to celebrate our 80th birthday, pianist Charles Rosen, author of two of the finest books of musicology of the past half century, celebrated his at the 92nd Street Y on Sunday by talking about and performing the music of Beethoven.

Mr. Rosen apologized in advance to those who thought he would discuss the works he was about to perform, but said doing so would focus the audience too sharply on the aspects discussed, leaving the performance as a whole largely unappreciated. He spoke instead about tangential topics as they related to Beethoven.

Asked about period performance practice, Mr. Rosen stated there were two surefire methods of killing a tradition. The first was to play a piece with no regard for its original performance technique; the second was to reproduce the work exactly as it had been originally played. He waxed rhapsodic about the best pianist he had heard in his lifetime, Sviatoslav Richter, who performed the late piano sonatas of Schubert with his piano lid closed and only the dimmest of lights shining in the hall, attempting to re-create under modern conditions the intimacy of a Schubertiade.

Mr. Rosen also discussed how the Beethoven piano sonatas became such universal favorites of recitalists. It was simply a matter of right place, right time. In Beethoven’s lifetime, only two of the 32 were ever performed at a public concert, but soon after his death, Franz Liszt invented the piano recital as a popular art form. Looking for serious material to offset his virtuosic opera fantasies, Liszt seized upon Beethoven as the ideal combination of profundity, difficulty, and showmanship — Mozart was much too tame and intimate for these rather flamboyant sessions.

After lunch, the audience settled in to hear Mr. Rosen traverse the last three sonatas. At this stage of his life, he is a serviceable craftsman but a superb artist. Hearing him play these pieces reminded me of what Irving Kolodin, of Saturday Review, had to say about these valedictory works. They contained, the critic wrote, “intellectual and emotional demands that defy the fleetest fingers if the mind that directs them is not equal to Beethoven’s own.” Here, the mind was equal, even if the fingers sometimes lagged behind.

Mr. Rosen is especially adept at displaying the shape of a piece, not just in the aggregate but also internally. In the E Major, Op. 109, he demonstrated the structure of the Adagio espressivo section — there are no movements per se — fashioning an unhurried and remarkably tasteful rendition. Similarly, when moving to the Opus 110, he took great pains to lay bare the architecture of the Adagio ma non troppo. His fluidity is impressive and he establishes a beautiful singing line even when unwanted notes occasionally peep through.

The final sonata, the C Minor, however, proved to be a bit much for Mr. Rosen this day. Even as he toiled to establish the dramatic tenor of the piece, which he did without bombast or melodrama, the fingerbreaking runs went off of the rails on three or four occasions. But this was still a richly rewarding experience — Beethoven realized by a true expert. There is so much froth and pandering in musical performance today, and so little intellectual grounding, that the privilege of hearing such an informed and honest effort is to be savored.