BTW, I can assure you demons can read your mind. Humans read each other minds all the time. If I can pull it off on a daily basis, I am sure Satan can.
I'm curious about this. My understanding is that they cannot read our actual thoughts, but that they can often determine them through some version of observation and inductive reasoning. They probably know us better than we know ourselves.
You are right about this. The demons cannot read our thoughts, but they observe carefully our outward demeanor, movements, gestures, and actions to determine our thoughts and passions.
From ConferenceVII of St. John Cassian
, who was commemorated yesterday on the New Calendar:CHAPTER XIV.
An objection, as to how we ought to believe that devils see into the thoughts of men.GERMANUS
: In this way, which you describe, those spirits cannot possibly see into our thoughts. But we think it utterly absurd to hold such an opinion, when Scripture says: "If the spirit of him that hath power ascend upon thee;" and again: "When the devil had put it into the heart of Simon Iscariot to betray the Lord." How then can we believe that our thoughts are not open to them, when we feel that for the most part they spring up and are nursed by their suggestions and instigation?CHAPTER XV.
The answer what devils can and what they cannot do in regard to the thoughts of men.SERENUS
: Nobody doubts that unclean spirits can influence the character of our thoughts, but this is by affecting them from without by sensible influences, i.e., either from our inclinations or from our words, and those likings to which they see that we are especially disposed. But they cannot possibly come near to those which have not yet come forth from the inmost recesses of the soul. And the thoughts too, which they suggest, whether they are actually or in a kind of way embraced, are discovered by them not from the nature of the soul itself, i.e., that inner inclination which lies concealed so to speak in the very marrow, but from motions and signs given by the outward man, as for example, when they suggest gluttony, if they have seen a monk raising his eyes anxiously to the window or to the sun, or inquiring eagerly what o'clock it is, they know that he has admitted the feeling of greediness. If when they suggest fornication they find him calmly submitting to the attack of lust, or see him perturbed in body, or at any rate not groaning as he ought under the wantonness of an impure suggestion, they know that the dart of lust is already fixed in his very soul. If they stir up incitements to grief, or anger, or rage, they can tell whether they have taken root in the heart by the movements of the body, and visible disturbances, when, for instance, they have noticed him either groaning silently, or panting with indignation or changing colour; and so they cunningly discover the fault to which he is given over. For they know that every one of us is enticed in a regular way by that one, to the incitement of which they see, by a sort of assenting motion of the body, that he has yielded his consent and agreement. And it is no wonder that this is discovered by those powers of the air, when we see that even clever men can often discover the state of the inner man from his mien and look and external bearing. How much more surely then can this be discovered by those who as being of a spiritual nature are certainly much more subtle and cleverer than men.http://www.osb.org/lectio/cassian/conf/book1/conf7.html#7.14