31 Indeed, a Christian formation and education which would only consider teaching the faithful the formulas of the Catechism and inculcating in their minds the principal precepts of moral theology, with a brief list of possible cases, without inspiring their souls and wills to act according to the instructions received, would run the serious risk of acquiring for the Church a passive flock. On the contrary, it is necessary that the sheep of the Christian flock not only listen to their Shepherd, but also know his voice, (52) and that the faithful willingly follow him to the pastures of eternal life, (53) so that one day they may receive from the Prince of Shepherds the "unfading crown of glory." (54) These sheep as We said, recognizing and following the Shepherd, who lays down his life for his sheep, (55) will give themselves entirely to him, and, obeying the Divine Will with the most ardent zeal, will lovingly and actively strive to bring into the one and only true fold all the other sheep, who not only are not following him, but have long been straying away from him, who is "the way, and the truth, and the life." (56)
Source: Princeps Pastorum (Vatican.va)