The Chautauqua Symphony Orchestra performs under circumstances that can only be termed unreasonable. The musicians rehearse and perform up to three programs a week, which would appear to work against any semblance of high standards. They often contend with climatic conditions that play tricks on reeds, keys, embouchures and more.

And yet, as it demonstrated Thursday in the Amphitheater, the ensemble can surmount most obstacles and turn in performances of remarkable depth and excitement. The principal offender on this occasion was rain, which fell throughout the concert, sometimes with defiant force, almost as if it intended to maintain a presence in the sonic textures.