Devotion disconnected from the sacraments? Not a good thing:
32. If the private and interior devotion of individuals were to neglect the august sacrifice of the altar and the sacraments, and to withdraw them from the stream of vital energy that flows from Head to members, it would indeed be sterile, and deserve to be condemned.
A dim view of the world, but when piety assists the “path of perfection,” then Pope Pius is speaking of the “indispensable.”
But when devotional exercises, and pious practices in general, not strictly connected with the sacred liturgy, confine themselves to merely human acts, with the express purpose of directing these latter to the Father in heaven, of rousing people to repentance and holy fear of God, of weaning them from the seductions of the world and its vice, and leading them back to the difficult path of perfection, then certainly such practices are not only highly praiseworthy but absolutely indispensable, because they expose the dangers threatening the spiritual life; because they promote the acquisition of virtue; and because they increase the fervor and generosity with which we are bound to dedicate all that we are and all that we have to the service of Jesus Christ. Genuine and real piety, which the Angelic Doctor calls “devotion,” and which is the principal act of the virtue of religion – that act which correctly relates and fitly directs (people) to God; and by which they freely and spontaneously give themselves to the worship of God in its fullest sense[Cf. Saint Thomas, Summa Theologica, IIª IIª³, q. 82, art. 1.] – piety of this authentic sort needs meditation on the supernatural realities and spiritual exercises, if it is to be nurtured, stimulated and sustained, and if it is to prompt us to lead a more perfect life.
Pope Pius XII speaks of knowledge here. Not surprising, given the era. The distinction of human beings in the mortal sphere strikes me as less due to our ability to absorb knowledge and more to our ability as spiritual beings to respond to God’s grace. The apostle Paul even cites that God works through human weakness, and that must surely include gaps in human understanding, even of religion. read anyway and see what you think:
For the Christian religion, practiced as it should be, demands that the will especially be consecrated to God and exert its influence on all the other spiritual faculties. But every act of the will presupposes an act of the intelligence, and before one can express the desire and the intention of offering oneself in sacrifice to the eternal Godhead, a knowledge of the facts and truths which make religion a duty is altogether necessary. One must first know, for instance, (humankind’s) last end and the supremacy of the Divine Majesty; after that, our common duty of submission to our Creator; and, finally, the inexhaustible treasures of love with which God yearns to enrich us, as well as the necessity of supernatural grace for the achievement of our destiny, and that special path marked out for us by divine Providence in virtue of the fact that we have been united, one and all, like members of a body, to Jesus Christ the Head.
Augustinian pessimism:
But further, since our hearts, disturbed as they are at times by the lower appetites, do not always respond to motives of love, it is also extremely helpful to let consideration and contemplation of the justice of God provoke us on occasion to salutary fear, and guide us thence to Christian humility, repentance and amendment.
This is true, but it is not the whole story. God chooses to work in spite of the so-called “lower appetites,” and often chooses people who have yet to embrace the explicit Savior, giving them a glimpse of the Divine, and sometimes even through worship.
A few long sentences, but much to comment upon here. Your thoughts?
Catholic Sensibility 
“The distinction of human beings in the mortal sphere strikes me as less due to our ability to absorb knowledge and more to our ability as spiritual beings to respond to God’s grace.”
Pius calls our ability to respond to God’s grace “the will” and he is making the formal and very classical argument that we can only incline our will toward something that we are aware of.
So it may be helpful to consider the will as the distinctive characteristic of the human person (rather than the reason, in line with Aristotle and Aquinas) but that still leaves the question of how one can love what one doesn’t know. I think that’s all he’s really getting at here.
Thanks for commenting, Ben.
I would suggest that awareness goes beyond an intellectual understanding. God’s grace is subtle and often arrives before us in unexpected ways. Art and relationships are two areas underappreciated in classical theology. Leaving art aside for the moment, I can attest that I have an “awareness” of my wife, and that out relationship, which operates often on an affective level, involves a response to grace.
I think one can know without the primary involvement of the mind.
And some recent reading of Karl Rahner has me thinking about the possibility of loving Christ by one’s actions without an explicit confession of faith. But I’ll have to give that some more … thought.