22 The special conditions of your country oblige Us to recall the necessary, obligatory, inescapable, care of the children, whose innocence is ensnared, whose education and Christian formation is thus so sorely tried. Two grave precepts are imposed on all Catholic Mexicans: the one negative, that is, to keep the children as far away as possible from the impious and corruptive school; the other positive, to give them complete and accurate religious instruction and the necessary assistance to maintain their spiritual life. Regarding the first point, a grave and delicate one, We recently took occasion to manifest Our thoughts. As regards religious instruction, although We know with what insistence you yourselves have recommended it to your priests and to your Faithful, yet We repeat that, this being one of the most important and capital problems of the Mexican Church today, it is necessary that what is so laudably practiced in some dioceses today should be extended to all the others, in such a manner that the priests and members of Catholic Action apply themselves with all ardor and at cost of any sacrifice to conserve for God and the Church these little ones, for whom the Divine Saviour has shown such predilection.
Source: Nos Es Muy Conocida (Vatican.va)