Here are some excerpts of chapter XI:
2. "And it must be known that, although all these things may happen to the bodily senses in the way of God, "we must never” rely upon them or accept them, but must always fly from them, without trying to ascertain whether they be good or evil;(...)"
3. "So he that esteems such things errs greatly and exposes himself to great peril of being deceived; in any case he will have within himself a complete impediment to the attainment of spirituality. For, as we have said, between spiritual things and all these bodily things there exists no kind of proportion whatever. And thus it may “always" be supposed that such things as these are more likely to be of the devil than of God; (…)"
4. “(…) they very easily become the means whereby error and presumption and vanity grow in the soul; since, as they are so palpable and material, they stir the senses greatly, and it appears to the judgment of the soul that they are of greater importance because they are more readily felt. Thus the soul goes after them, abandoning faith and thinking that the light which it receives from them is the guide and means to its desired goal, which is union with God. But the more attention it pays to such things, the farther it strays from the true way and means, which are faith."
5. "And, besides all this, when the soul sees that such extraordinary things happen to it, it is often visited, insidiously and secretly by a certain complacency, so that it thinks itself to be of some importance in the eyes of God; which is contrary to humility. The devil, too, knows how to insinuate into the soul a secret satisfaction with itself, which at times becomes very evident; wherefore he frequently represents these objects to the senses, setting before the eyes figures of saints and most beauteous lights; and before the ears words very much dissembled; and representing also sweetest perfumes, delicious tastes (281) and things delectable to the touch; to the end that, by producing desires for such things, he may "lead the soul into much evil". These representations and feelings, therefore, “must always be rejected”; for, even though some of them be of God, He is not offended by their rejection, nor is the effect and fruit which He desires to produce in the soul by means of them any the less surely received because the soul rejects them and desires them not."
7. The soul, then, must never presume to desire to receive them, even though, as I say, they be of God; for, if it desire to receive them, there follow six inconveniences.
1. The first is that faith grows gradually less (…)
2. Secondly, if they be not rejected, they are a hindrance to the spirit (…)
3. Thirdly, the soul becomes attached to these things and advances not to true resignation and detachment of spirit.
4. Fourthly, it begins to lose the effect of them and the inward spirituality which they cause it (…)
5. Fifthly, the soul begins to lose the favours of God, because it accepts them as though they belonged to it and profits not by them as it should.
6. Sixthly, a readiness to accept them opens the door to the devil that he may deceive the soul by other things like to them (…)
8. It is always well, then, that the soul should reject these things, and close its eyes to them, whencesoever they come. For, unless it does so, it will prepare the way for those things that come from the devil, and will give him such influence that, not only will his visions come in place of God’s, but his visions will begin to increase, and those of God to cease, in such manner that the devil will have all the power and God will have none. So it has happened to many incautious and ignorant souls, who rely on these things to such an extent that many of them have found it hard to return to God in purity of faith; and many have been unable to return, so securely has the devil rooted himself in them; for which reason it is well to resist and reject them all. For, by the rejection of evil visions, the errors of the devil are avoided, and by the rejection of good visions no hindrance is offered to faith and the spirit harvests the fruit of them.
12. It is clear, then, that these sensual apprehensions and visions cannot be a means to union, since they bear no proportion to God; and this was one of the reasons why Christ desired that the Magdalene and Saint Thomas should not touch Him. And so the devil rejoices greatly when a soul desires to receive revelations, and when he sees it inclined to them, for he has then a great occasion and opportunity to insinuate errors and, in so far as he is able, to derogate from faith; for, as I have said, he renders the soul that desires them very gross, and at times even leads it into many temptations and unseemly ways.
(22) All this shows clearly the error of imprudent directors who, impelled by curiosity, are concerned with souls favored by visions and revelations.(23) This curiosity is a deformation of the spirit which casts the soul into illusion and trouble, and turns it away from humility through vain complacency in extraordinary ways.
22. Ibid., Bk. III, chaps. 9, 12 / Bk II, chap. 22
St. John of the Cross and excepts from The Ascent of Mount Carmel
And to top it off, just in case one feels inclined to believe something of this nature or someone with these powers, remember:
Private revelations may not be published without the approbation of ecclesiastical authority.
6. Cf. the decree of Urban VIII, March 13, 1625, which was confirmed by Clement IX, May 23, 1668.