For several years, my wife Alice and I have been attending a summer concert that takes place at the Windfall Dutch Barn in Salt Springville, New York. There’s always a different group that comes to entertain, but musician and composer Carlton Clay usually enthusiastically presides over the event. One year, conductor and pianist Charles Schneider, accompanied by four singers, came to explain and then demonstrate how Leonard Bernstein almost mathematically put together “West Side Story”—not to mention words by Stephen Sondheim. The result was both ear opening and entertaining.…