After years of hanging around my pal Milton Moore, the retired-but-still-contributing fine arts writer for The Day, it finally occurred to me to ask him, "Hey, this classical music stuff: What are all those 'Op.' things about?"

Milton laughed and clubbed me in the head with a bowling pin because this came AFTER he foolishly sent me to interview serialist/avante garde composer Pierre Boulez who, it turned out, had never heard of Foghat and gave me an odd look when I asked him about them.

In any case, Milton informed me that "Op." is short for "opus" and is used to designate how a composer's work is chronologically catalogued. Therefore, if we see a musical program, for example, that includes Brahms' Piano Trios Op. 101 in C minor, Op. 87 in C major and Op. 8 in B major, we conclude that it's a pretty cool program because A) not only did Brahmswrite just three trios for piano, violin and cello, but B) in his incredibly prolific career, a concert ranging from Op. 8 to Op. 101 means the audience gets to experience works at both the beginning and end of his brilliant career.

This is precisely what you can expect Friday in the Katharine Hepburn Cultural Arts Center. It's a presentation by the Chestnut Hill Concert Series, and artistic director/cellist Ronald Thomas will be joined by pianist Mihae Lee and violinist Arturo Delmoni.

Chestnut Hill Concert Series, 8 p.m. Friday, Katharine Hepburn Cultural Arts Center, 300 Main St., Old Saybrook; $35; (860) 510-0473.