MONTREAL — The first movement of Brahms’s Trio Op. 8 was coming to a rip-roaring conclusion, as it must. André Laplante (piano), Augustin Dumay (violin) and Matt Haimovitz (cello) were putting their fingers and forearms into it, as well as their hearts. Big crescendo, big fortissimo. Hair on the fly.

I would have bet the ranch on an explosion of applause. The ranch. This was, after all, the OSM-organized marathon called A Cool Classical Journey, attracting veterans and newcomers alike to Place des Arts (and in this case, the Cinquième Salle). No sitting on ceremony here, waiting for the entire piece to end.

So we arrive at the cadence. Dum-dum-dahhhhhh. Nothing. Silence. The musicians shuffle, shift their weight and glance at each other, the way musicians do. And they get started on the Scherzo.

There was no such restraint earlier that Saturday. Applause was persistent after first movements, and even after some delicate adagios. Violinist Alexandre Da Costa, collaborating with pianist David Jalbert in the same room and in similar standard fare — Beethoven’s Spring Sonata and Brahms’s Sonata Op. 108 — got a round after almost every movement.

Violinist Andrew Wan and pianist Philip Chiu (Mozart’s E Minor Sonata and Franck) had similar luck in the Studio-théàtre. Although it should be said that the coda of the first movement of the Franck is so rousing that even observers of the no-clapping convention are apt to put their hands together. Same problem after the first movement of Tchaikovsky’s Violin Concerto.

But back to the paradox of the moment. Why no applause after the allegro con brio of Op. 8? The only plausible theory that I can propose: This mini-concert started at 8:30 p.m., well into the Dracula shift, when classical types rise from their graves and stalk the Earth.

These are the people who give up their Saturday nights for great music. They were also the people who packed the Maison symphonique at 9:30 p.m. for the final concert by the OSM under Kent Nagano. No pesky clapping there. Just big ovations where they mattered.

Da Costa’s concert started at 6:45 p.m., the end of the afternoon, at least in the summer. These were not the classical undead. These were real people spending their Saturday afternoon getting to know the glories of great music. And, of course, clapping where not appropriate.

Let me remind readers once again that my prescriptions regarding applause are not my own or those of high-handed oligarchies. They are accepted (and generally observed) by audiences around the world. Opposite conventions exist in jazz. Clapping after a solo is expected. If it is withheld, the artists can only assume the audience is ignorant, inattentive or profoundly unimpressed by what they hear.

A similar dynamic is at work in the classical concert hall. Only the polarity is reversed. It is the positive act of clapping after a first movement that implies audience unfamiliarity with the rules.

There is a perceptual rollout after invasive clapping, however subtle. Performances of great symphonies and sonatas are communal. The quality of listening matters. “It disconnects a cable somewhere,” was the image one OSM musician used a few years ago to describe the effect of an ill-timed round of applause.