A couple of months ago (when the world was still normal), Martha and I went to see the St. Louis Symphony Orchestra perform a program that included Ravel’s “Bolero.”

We were familiar with the piece even before Bo Derek used it to seduce Dudley Moore in “Ten,” but we’d never heard it played in full and so beautifully. One of the things that struck us was that the pace of “Bolero” never changes from start to finish. Our memories would have sworn otherwise, but there was the proof, in person. From its first moments of just a snare drum to the crescendo of all the musicians playing together, the volume changes, but never the tempo.

Here’s a sheltered-at-home version performed recently by the members of the New York Philharmonic…