38 While still on earth, He instructed us by precept, counsel and warning in words that shall never pass away, and will be spirit and life to all men of all times. Moreover He conferred a triple power on His Apostles and their successors, to teach, to govern, to lead men to holiness, making this power, defined by special ordinances, rights and obligations, the fundamental law of the whole Church.
Source: Mystici Corporis Christi (Vatican.va)