Our guardian angels can help us with the Matter of Sin. Because sin affects our intellects and imaginations, we can ask our guardian angels to enlighten us.
Here is what St. Thomas says. See here.
Natural reason, which is immediately from God, can be strengthened by an angel so that he may obtain from creatures a more perfect knowledge of God.
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Intellectual operation and enlightenment can be understood in two ways.
First, on the part of the object understood; thus whoever understands or is enlightened, knows that he understands or is enlightened, because he knows that the object is made known to him.
Secondly, on the part of the principle; and thus it does not follow that whoever understands a truth, knows what the intellect is, which is the principle of the intellectual operation. In like manner not everyone who is enlightened by an angel, knows that he is enlightened by him.
If we ask our angels to help illuminate our minds, they will do so.
Here is St. Thomas again on this subject:
The demon cannot put thoughts in our minds by causing them from within, since the act of the cogitative faculty is subject to the will; nevertheless the devil is called the kindler of thoughts, inasmuch as he incites to thought, by the desire of the things thought of, by way of persuasion, or by rousing the passions. Damascene calls this because such a work is accomplished within. But good thoughts are attributed to a higher principle, namely, God, though they may be procured by the ministry of the kindling "a putting in" angels.
The will is moved only by God, but angels aid us in our intellect, our imagination and our senses.
Again, Thomas, and this is a long section on the influence of the imagination by both demons and the good angels:
Both a good and a bad angel by their own natural power can move the human imagination. This may be explained as follows. For it was said above (Question 110, Article 3), that corporeal nature obeys the angel as regards local movement, so that whatever can be caused by the local movement of bodies is subject to the natural power of the angels. Now it is manifest that imaginative apparitions are sometimes caused in us by the local movement of animal spirits and humors. Hence Aristotle says (De Somn. et Vigil.) [De Insomniis iii.], when assigning the cause ofvisions in dreams, that "when an animal sleeps, the blood descends in abundance to the sensitive principle, and movements descend with it," that is, the impressions left from the movements are preserved in the animal spirits, "and move the sensitive principle"; so that a certain appearance ensues, as if the sensitive principle were being then changed by the external objects themselves. Indeed, the commotion of the spirits and humors may be so great that such appearances may even occur to those who are awake, as is seen in mad people, and the like. So, as this happens by a natural disturbance of the humors, and sometimes also by the will of man who voluntarily imagines what he previously experienced, so also the same may be done by the power of a good or a bad angel, sometimes with alienation from the bodily senses, sometimes without such alienation.
Reply to Objection 1. The first principle of the imagination is from the sense in act. For we cannot imagine what we have never perceived by the senses, either wholly or partly; as a man born blind cannot imagine color. Sometimes, however, the imagination is informed in such a way that the act of the imaginative movement arises from the impressions preserved within.
Reply to Objection 2. An angel changes the imagination, not indeed by the impression of an imaginative form in no way previously received from the senses (for he cannot make a man born blind imagine color), but by local movement of the spirits and humors, as above explained.
Reply to Objection 3. The commingling of the angelic spirit with the human imagination is not a mingling of essences, but by reason of an effect which he produces in the imagination in the way above stated; so that he shows man what he [the angel] knows, but not in the way he knows.
Reply to Objection 4. An angel causing an imaginative vision, sometimes enlightens the intellect at the same time, so that it knows what these images signify; and then there is not deception. But sometimes by the angelic operation the similitudes of things only appear in the imagination; but neither then is deception caused by the angel, but by the defect in the intellect to whom such things appear. Thus neither was Christ a cause of deception when He spoke many things to the people inparables, which He did not explain to them.
One can see how important it is for one to control one's eyes, ears, indeed all the senses, and discipline the imagination.
That the angels want to help us is fantastic, but one cannot assume help if one refuses to discipline one's own mind.
Such is the danger and down-side of the matter of sin.
to be continued...