If only one of Paul McCartney's varied musical strengths carries his oratorio, Ecce Cor Meum (Behold My Heart), it is his astonishing melodic talent: indeed, it is because of the piece's undeniable tunefulness that it is at all viable. This grandiose, neo-Romantic work for soprano, mixed choir, boy choir, and orchestra would seem unbearably tedious were it not for the chains of attractive themes that are laced throughout, and the monumental structure would collapse under its ponderous weight were it not for the light, lyrical touches that hold it up…