17 For to be right and good, worship of the Mother of God ought to spring from the heart; acts of the body have here neither utility nor value if the acts of the soul have no part in them. Now these latter can only have one object, which is that we should fully carry out what the divine Son of Mary commands. For if true love alone has the power to unite the wills of men, it is of the first necessity that we should have one will with Mary to serve Jesus our Lord. What this most prudent Virgin said to the servants at the marriage feast of Cana she addresses also to us: "Whatsoever he shall say to you, do ye" ( John ii., 5). Now here is the word of Jesus Christ: "If you would enter into life, keep the commandments" ( Matt . xix., 17). Let them each one fully convince himself of this, that if his piety towards the Blessed Virgin does not hinder him from sinning, or does not move his will to amend an evil life, it is a piety deceptive and Iying, wanting as it is in proper effect and its natural fruit.
Source: Ad Diem Illum Laetissimum (Vatican.va)