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. 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. 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. 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.