These are not chatty and trivial, but deadly serious writings on a host of subjects by a Saint whose ardor of expression has probably never been surpassed in print! These are not chatty and trivial, but deadly serious writings on a host of subjects by a Saint whose ardor of expression has probably never been surpassed in print! Our Lord told St. Margaret Mary that there were three hearts in perfect harmony: His own, St. Claude de Ia Colombiere's and that of St. Margaret Mary herself (1647-1690), whom He chose to be the Apostle of devotion to His Sacred Heart, a devotion which has shaped the Church's piety for over three centuries.