Lorenzo Scupoli, enhanced by Saint Nicodemus of the Holy Mountain, and Saint Theophan the Recluse. "Unseen Warfare".
The reason why we have wrong judgment of the things we mentioned earlier is that we do not look deeply into them to see what they are, but conceive a liking for them or a dislike of them from the very first glance, judging by appearances. These likes and dislikes prejudice our mind and darken it; and so it cannot form a. right judgment of things as they really are. So, my brother, if you wish to be free of this prelest in your mind, keep strict attention over yourself; and when you see a thing with your eyes, or visualise it in your mind, keep a firm grip on your desires and do not allow yourself at the first glance either to conceive a liking for the thing or a dislike for it, but examine it in a detached way with the mind alone. Unobscured by passion, the mind then remains in a state natural to it, which is free and pure, and has the possibility to know the truth and to penetrate into the depths of a thing, where evil is often concealed under a deceptively attractive exterior and where good is sometimes hidden under a bad appearance.
But if desire comes first and at once either likes a thing or turns away from it, your mind no longer has the possibility to know it rightly as it should. For if this predisposition, or rather this passion precedes every judgment, it enters within, becomes a wall between the mind and the thing and, obscuring the mind, makes it form its judgment from passion. In other words, it sees it not as it really is, which strengthens still more its original predisposition. The further this predisposition runs ahead, or the more it likes or dislikes a thing, the more it obscures the mind in relation to it, until it darkens the mind completely. Then passion in relation to this thing reaches its ultimate limits, so that it appears to a man either as the most desirable or the most hateful of all the things he ever liked or disliked. Thus it happens that when the rule I have indicated is not observed, that is, when desire is not restrained from forming likes and dislikes before a thing is properly examined, then both these powers of the soul—mind and will—always work wrongly, plunging ever deeper and deeper from darkness to darkness, and from sin to sin.
So watch, my beloved, with all attention and protect yourself from liking or disliking a thing out of passion, before you have had time to examine it properly in the light of reason and the just word of the Divine Scriptures, in the light of grace and prayer, and with the help of the judgment of your spiritual father; otherwise you may sin in taking for evil what is truly good, and for good what is truly evil. This mostly happens in the case of certain actions, which are good and holy in themselves, but which according to circumstances,) namely that if they are done at a wrong time, or are out of place, or arc not done in the right measure, cause, considerable harm to those who do them, We know from experience what afflictions are suffered by some through such worthy and holy deeds.