How faith is dark night to the soul. This is proved with arguments and quotations and figures from Scripture.

Faith, say the theologians, is a habit of the soul, certain and obscure. And the reason for its being an obscure habit is that it makes us believe truths revealed by God Himself, which transcend all natural light, and exceed all human understanding, beyond all proportion. Hence it follows that, for the soul, this excessive light of faith which is given to it is thick darkness, for it overwhelms greater things and does away with small things, even as the light of the sun overwhelms all other lights whatsoever, so that when it shines and disables our visual faculty they appear not to be lights at all. So that it blinds it and deprives it of the sight that has been given to it, inasmuch as its light is great beyond all proportion and transcends the faculty of vision. Even so the light of faith, by its excessive greatness, oppresses and disables that of the understanding; for the latter, of its own power, extends only to natural knowledge, although it has a faculty E .p.: an obediential faculty’ [potencia obediencial]: this phrase is borrowed from the Schoolmen. Among the various divisions of the faculty are two, natural and obediential. The first is that which is directed towards an act within the sphere of nature, such as the cooling action of water and the heating action of fire; the second is directed towards an act which exceeds these powers, brought about by God, Who is outside the laws of nature and can therefore work outside the natural domain. This obediential faculty (called also receptive’ or passive’) frequently figures in mystical theology, since it is this that disposes the faculties of the soul for the supernatural reception of the gifts of grace, all of which exceed natural capacity. for the supernatural, whenever Our Lord is pleased to give it supernatural activity.

2. Wherefore a man can know nothing by himself, save after a natural manner, E.p.: a natural manner which has its beginning in the senses.’ Here the Saint expounds a principle of scholastic philosophy summarized in the axiom: Nihil est in intellectu quin prius non fuerit in sensu. This principle, like many other great philosophical questions, has continually been debated. St. John of the Cross will be found as a rule to follow the philosophy most favored by the Church and is always rigidly orthodox. which is only that which he attains by means of the senses. For this cause he must have the phantasms and the forms of objects present in themselves and in their likenesses; otherwise it cannot be, for, as philosophers say: Ab objecto et potentia paritur notitia. That is: From the object that is present and from the faculty, knowledge is born in the soul. Wherefore, if one should speak to a man of things which he has never been able to understand, and whose likeness he has never seen, he would have no more illumination from them whatever than if naught had been said of them to him. I take an example. If one should say to a man that on a certain island there is an animal which he has never seen, and give him no idea of the likeness of that animal, that he may compare it with others that he has seen, he will have no more knowledge of it, or idea of its form, than he had before, however much is being said to him about it. And this will be better understood by another and a more apt example. If one should describe to a man that was born blind, and has never seen any colour, what is meant by a white colour or by a yellow, he would understand it but indifferently, however fully one might describe it to him; for, as he has never seen such colours or anything like them by which he may judge them, only their names would remain with him; for these he would be able to comprehend through the ear, but not their forms or figures, since he has never seen them.

3. Even so is faith with respect to the soul; it tells us of things which we have never seen or understood, nor have we seen or understood aught that resembles them, since there is naught that resembles them at all. And thus we have no light of natural knowledge concerning them, since that which we are told of them bears no relation to any sense of ours; we know it by the ear alone, believing that which we are taught, bringing our natural light into subjection and treating it as if it were not. [Lit., ‘subjecting and blinding our natural light.’] For, as Saint Paul says, Fides ex auditu. Romans x, 17. As though he were to say: Faith is not knowledge which enters by any of the senses, but is only the consent given by the soul to that which enters through the ear.

4. And faith far transcends even that which is indicated by the examples given above. For not only does it give no information and knowledge, but, as we have said, it deprives us of all other information and knowledge, and blinds us to them, so that they cannot judge it well. For other knowledge can be acquired by the light of the understanding; but the knowledge that is of faith is acquired without the illumination of the understanding, which is rejected for faith; and in its own light, if that light be not darkened, it is lost. Wherefore Isaias said: Si non credideritis, non intelligetis. Isaias vii, 9. So Alc. The passage seems to be taken from the Septuagint. [The Vulgate has non permanebitis.] That is: If ye believe not, ye shall not understand. It is clear, then, that faith is dark night for the soul, and it is in this way that it gives it light; and the more the soul is darkened, the greater is the light that comes to it. For it is by blinding that it gives light, according to this saying of Isaias. For if ye believe not, ye shall not (he says) have light. [Lit., If ye believe not, that is, ye shall not have light.’] And thus faith was foreshadowed by that cloud which divided the children of Israel and the Egyptians when the former were about to enter the Red Sea, whereof Scripture says: Erat nubes tenebrosa, et illuminans noctem. Exodus xiv, 20. This is to say that that cloud was full of darkness and gave light to the night.

5. A wondrous thing it is that, though it was dark, it should give light to the night. This was said to show that faith, which is a black and dark cloud to the soul (and likewise is night, since in the presence of faith the soul is deprived of its natural light and is blinded), can with its darkness give light and illumination to the darkness of the soul, for it was fitting that the disciples should thus be like the master. For man, who is in darkness, could not fittingly be enlightened save by other darkness, even as David teaches us, saying: Dies diei eructat verbum et nox nocti indicat scientiam. Psalm xviii, 3 [A.V., xix, 2]. Which signifies: Day unto day uttereth and aboundeth in speech, and night unto night showeth knowledge. Which, to speak more clearly, signifies: The day, which is God in bliss, where it is day to the blessed angels and souls who are now day, communicates and reveals to them the Word, which is His Son, that they may know Him and enjoy Him. And the night, which is faith in the Church Militant, where it is still night, shows knowledge is night to the Church, and consequently to every soul, which knowledge is night to it, since it is without clear beatific wisdom; and, in the presence of faith, it is blind as to its natural light.

6. So that which is to be inferred from this that faith, because it is dark night, gives light to the soul, which is in darkness, that there may come to be fulfilled that which David likewise says to this purpose, in these works: Et nox illuminatio mea in deliciis meis. Psalm cxxxviii, 11 [A.V., cxxxix, 11]. Which signifies: the night will be illumination in my delights. Which is as much as to say: In the delights of my pure contemplation and union with God, the night of faith shall be my guide. Wherein he gives it clearly to be understood that the soul must be in darkness in order to have light for this road.