When Claudio Abbado “conducts these days, it is a choice occasion. At 74, his schedule reduced after his recovery from stomach cancer six years ago, Mr. Abbado has mostly turned away from the kind of grand institutions he once led — La Scala, the Vienna State Opera, the Berlin Philharmonic — and now pours his limited energies mainly into a few bursts of concerts. He has distilled away the distractions of modern conductorhood, like administration, dealing with unions and constant travel. He plays the music he wants with the musicians he chooses.”