The third evil that the desires cause in the soul is that they blind and darken it. Even as vapours darken the air and allow not the bright sun to shine; or as a mirror that is clouded over cannot receive within itself a clear image; or as water defiled by mud reflects not the visage of one that looks therein; even so the soul that is clouded by the desires is darkened in the understanding and allows neither [Lit., gives no occasion either for,’ etc.] the sun of natural reason nor that of the supernatural Wisdom of God to shine upon it and illumine it clearly. And thus David, speaking to this purpose, says: Comprehenderunt me iniquitates meae, et non potui, ut viderem. Psalm xxxix, 13 [A.V., xl, 12.] Which signifies: Mine iniquities have taken hold upon me, and I could have no power to see.

2. And, at this same time, when the soul is darkened in the understanding, it is benumbed also in the will, and the memory becomes dull and disordered in its due operation. For, as these faculties in their operations depend upon the understanding, it is clear that, when the understanding is impeded, they will become disordered and troubled. And thus David says: Anima mea turbata est valde. Psalm vi, 4 [A.V., vi, 3]. That is: My soul is sorely troubled. Which is as much as to say, disordered in its faculties.’ For, as we say, the understanding has no more capacity for receiving enlightenment from the wisdom of God than has the air, when it is dark, for receiving enlightenment from the sun; neither has the will any power to embrace God within itself in pure love, even as the mirror that is clouded with vapour has no power to reflect clearly within itself any visage, [Lit., the present visage.’] and even less power has the memory which is clouded by the darkness of desire to take clearly upon itself the form of the image of God, just as the muddled water cannot show forth clearly the visage of one that looks at himself therein.

3. Desire blinds and darkens the soul; for desire, as such, is blind, since of itself it has no understanding in itself, the reason being to it always, as it were, a child leading a blind man. And hence it comes to pass that, whensoever the soul is guided by its desire, it becomes blind; for this is as if one that sees were guided by one that sees not, which is, as it were, for both to be blind. And that which follows from this is that which Our Lord says through Saint Matthew: Si caecus caeco ducatum praestet, ambo in foveam cadunt. St. Matthew xv, 14. If the blind lead the blind, both fall into the pit.’ Of little use are its eyes to a moth, since desire for the beauty of the light dazzles it and leads it into the flame. [hoguera. More exactly: fire,’ bonfire,’ blaze.’] And even so we may say that one who feeds upon desire is like a fish that is dazzled, upon which the light acts rather as darkness, preventing it from seeing the snares which the fishermen are preparing for it. This is very well expressed by David himself, where he says of such persons: Supercecidit ignis, et non viderunt solem. Psalm lvii, 9 [cf. A.V., lviii, 8]. Which signifies: There came upon them the fire, which burns with its heat and dazzles with its light. And it is this that desire does to the soul, enkindling its concupiscence and dazzling its understanding so that it cannot see its light. For the cause of its being thus dazzled is that when another light of a different kind is set before the eye, the visual faculty is attracted by that which is interposed so that it sees not the other; and, as the desire is set so near to the soul as to be within the soul itself, the soul meets this first light and is attracted by it; and thus it is unable to see the light of clear understanding, neither will see it until the dazzling power of desire is taken away from it.

4. For this reason one must greatly lament the ignorance of certain men, who burden themselves with extraordinary penances and with many other voluntary practices, and think that this practice or that will suffice to bring them to the union of Divine Wisdom; but such will not be the case if they endeavour not diligently to mortify their desires. If they were careful to bestow half of that labour on this, they would profit more in a month than they profit by all the other practices in many years. For, just as it is necessary to till the earth if it is to bear fruit, and unless it be tilled it bears naught but weeds, just so is mortification of the desires necessary if the soul is to profit. Without this mortification, I make bold to say, the soul no more achieves progress on the road to perfection and to the knowledge of God of itself, however many efforts it may make, than the seed grows when it is cast upon untilled ground. Wherefore the darkness and rudeness of the soul will not be taken from it until the desires be quenched. For these desires are like cataracts, or like motes in the eye, which obstruct the sight until they be taken away.

5. And thus David, realizing how blind are these souls, and how completely impeded from beholding the light of truth, and how wroth is God with them, speaks to them, saying: Priusquam intelligerent spinae vestrae rhamnum: sicut viventes, sic in ira absorber eos. Psalm lvii, 10 [A.V., lviii, 9]. And this is as though He had said: Before your thorns (that is, your desires) harden and grow, changing from tender thorns into a thick hedge and shutting out the sight of God even as oft-times the living find their thread of life broken in the midst of its course, even so will God swallow them up in His wrath. For the desires that are living in the soul, so that it cannot understand Him, [Lit., before it can understand God.’] will be swallowed up by God by means of chastisement and correction, either in this life or in the next, and this will come to pass through purgation. And He says that He will swallow them up in wrath, because that which is suffered in the mortification of the desires is punishment for the ruin which they have wrought in the soul.

6. Oh, if men but knew how great is the blessing of Divine light whereof they are deprived by this blindness which proceeds from their affections and desires, and into what great hurts and evils these make them to fall day after day, for so long as they mortify them not! For a man must not rely upon a clear understanding, or upon gifts that he has received from God, and think that he may indulge his affection or desire, and will not be blinded and darkened, and fall gradually into a worse estate. For who would have said that a man so perfect in wisdom and the gifts of God as was Solomon would have been reduced to such blindness and torpor of the will as to make altars to so many idols and to worship them himself, when he was old? 3 Kings [A.V., 1 Kings] xi, 4. Yet no more was needed to bring him to this than the affection which he had for women and his neglect to deny the desires and delights of his heart. For he himself says concerning himself, in Ecclesiastes, that he denied not his heart that which it demanded of him. Ecclesiastes ii, 10. And this man was capable of being so completely led away by his desires that, although it is true that at the beginning he was cautious, nevertheless, because he denied them not, they gradually blinded and darkened his understanding, so that in the end they succeeded in quenching that great light of wisdom which God had given him, and therefore in his old age he foresook God.

7. And if unmortified desires could do so much in this man who knew so well the distance that lies between good and evil, what will they not be capable of accomplishing by working upon our ignorance? For we, as God said to the prophet Jonas concerning the Ninivites, cannot discern between [Lit., we . . . know not what there is between.‘] our right hand and our left. Jonas iv, 11. At every step we hold evil to be good, and good, evil, and this arises from our own nature. What, then, will come to pass if to our natural darkness is added the hindrance of desire? [Lit., is added desire.’] Naught but that which Isaias describes thus: Palpavimus, sicut caeci parietem, et quasi absque oculis adtrectavimus: impegimus meridie, quasi in tenebris. Isaias lix, 10. The prophet is speaking with those who love to follow these their desires. It is as if he had said: We have groped for the wall as though we were blind, and we have been groping as though we had no eyes, and our blindness has attained to such a point that we have stumbled at midday as though it were in the darkness. For he that is blinded by desire has this property, that, when he is set in the midst of truth and of that which is good for him, he can no more see them than if he were in darkness.