Somewhat reluctantly, out of respect for a venerable tradition, we publish the Dark Night as a separate treatise, though in reality it is a continuation of the Ascent of Mount Carmel and fulfills the undertakings given in it:
The first night or purgation is of the sensual part of the soul, which is treated in the present stanza, and will be treated in the first part of this book. And the second is of the spiritual part; of this speaks the second stanza, which follows; and of this we shall treat likewise, in the second and the third part, with respect to the activity of the soul; and in the fourth part, with respect to its passivity. 
This ‘fourth part’ is the Dark Night. Of it the Saint writes in a passage which follows that just quoted:
And the second night, or purification, pertains to those who are already proficient, occurring at the time when God desires to bring them to the state of union with God. And this latter night is a more obscure and dark and terrible purgation, as we shall say afterwards. 
In his three earlier books he has written of the Active Night, of Sense and of Spirit; he now proposes to deal with the Passive Night, in the same order. He has already taught us how we are to deny and purify ourselves with the ordinary help of grace, in order to prepare our senses and faculties for union with God through love. He now proceeds to explain, with an arresting freshness, how these same senses and faculties are purged and purified by God with a view to the same end – that of union. The combined description of the two nights completes the presentation of active and passive purgation, to which the Saint limits himself in these treatises, although the subject of the stanzas which he is glossing is a much wider one, comprising the whole of the mystical life and ending only with the Divine embraces of the soul transformed in God through love.
The stanzas expounded by the Saint are taken from the same poem in the two treatises. The commentary upon the second, however, is very different from that upon the first, for it assumes a much more advanced state of development. The Active Night has left the senses and faculties well prepared, though not completely prepared, for the reception of Divine influences and illuminations in greater abundance than before. The Saint here postulates a principle of dogmatic theology – that by himself, and with the ordinary aid of grace, man cannot attain to that degree of purgation which is essential to his transformation in God. He needs Divine aid more abundantly. ‘However greatly the soul itself labours,’ writes the Saint, ‘it cannot actively purify itself so as to be in the least degree prepared for the Divine union of perfection of love, if God takes not its hand and purges it not in that dark fire.' 
The Passive Nights, in which it is God Who accomplishes the purgation, are based upon this incapacity. Souls ‘begin to enter’ this dark night when God draws them forth from the state of happiness – which is that of those who are already contemplatives – to the end that, after passing through it, they may arrive at the state of the perfect, which is that of the Divine union of the soul with God. 
Before explaining the nature and effects of this Passive Night, the Saint touches, in passing, upon certain imperfections found in those who are about to enter it and which it removes by the process of purgation. Such travelers are still untried proficients, who have not yet acquired mature habits of spirituality and who therefore still conduct themselves as children. The imperfections are examined one by one, following the order of the seven deadly sins, in chapters (ii-viii) which once more reveal the author’s skill as a director of souls. They are easy chapters to understand, and of great practical utility, comparable to those in the first book of the Ascent which deal with the active purgation of the desires of sense.
In Chapter viii, St. John of the Cross begins to describe the Passive Night of the senses, the principal aim of which is the purgation or stripping of the soul of its imperfections and the preparation of it for fruitive union. The Passive Night of Sense, we are told, is ‘common’ and ‘comes to many,’ whereas that of Spirit ‘is the portion of very few.’  The one is ‘bitter and terrible’ but ‘the second bears no comparison with it,’ for it is ‘horrible and awful to the spirit.'  A good deal of literature on the former Night existed in the time of St. John of the Cross and he therefore promises to be brief in his treatment of it. Of the latter, on the other hand, he will ‘treat more fully … since very little has been said of this, either in speech or in writing, and very little is known of it, even by experience.' 
Having described this Passive Night of Sense in Chapter viii, he explains with great insight and discernment how it may be recognized whether any given aridity is a result of this Night or whether it comes from sins or imperfections, or from frailty or lukewarmness of spirit, or even from indisposition or ‘humours’ of the body. The Saint is particularly effective here, and we may once more compare this chapter with a similar one in the Ascent (II, xiii) – that in which he fixes the point where the soul may abandon discursive meditation and enter the contemplation which belongs to loving and simple faith.
Both these chapters have contributed to the reputation of St. John of the Cross as a consummate spiritual master. And this not only for the objective value of his observations, but because, even in spite of himself, he betrays the sublimity of his own mystical experiences. Once more, too, we may admire the crystalline transparency of his teaching and the precision of the phrases in which he clothes it. To judge by his language alone, one might suppose at times that he is speaking of mathematical, rather than of spiritual operations.
In Chapter x, the Saint describes the discipline which the soul in this Dark Night must impose upon itself; this, as might be logically deduced from the Ascent, consists in ‘allowing the soul to remain in peace and quietness,’ content ‘with a peaceful and loving attentiveness toward God.’  Before long it will experience enkindlings of love (Chapter xi), which will serve to purify its sins and imperfections and draw it gradually nearer to God; we have here, as it were, so many stages of the ascent of the Mount on whose summit the soul attains to transforming union. Chapters xii and xiii detail with great exactness the benefits that the soul receives from this aridity, while Chapter xiv briefly expounds the last line of the first stanza, and brings to an end what the Saint desires to say with respect to the first Passive Night.
At only slightly greater length St. John of the Cross describes the Passive Night of the Spirit, which is at once more afflictive and more painful than those which have preceded it. This, nevertheless, is the Dark Night par excellence, of which the Saint speaks in these words: ‘The night which we have called that of sense may and should be called a kind of correction and restraint of the desire rather than purgation. The reason is that all the imperfections and disorders of the sensual part have their strength and root in the spirit, where all habits, both good and bad, are brought into subjection, and thus, until these are purged, the rebellions and depravities of sense cannot be purged thoroughly.’ 
Spiritual persons, we are told, do not enter the second night immediately after leaving the first; on the contrary, they generally pass a long time, even years, before doing so,  for they still have many imperfections, both habitual and actual (Chapter ii). After a brief introduction (Chapter iii), the Saint describes with some fullness the nature of this spiritual purgation or dark contemplation referred to in the first stanza of his poem and the varieties of pain and affliction caused by it, whether in the soul or in its faculties (Chapters iv-viii). These chapters are brilliant beyond all description; in them we seem to reach the culminating point of their author’s mystical experience; any excerpt from them would do them an injustice. It must suffice to say that St. John of the Cross seldom again touches those same heights of sublimity.
Chapter ix describes how, although these purgations seem to blind the spirit, they so so only to enlighten it again with a brighter and intenser light, which it is preparing itself to receive with greater abundance. The following chapter makes the comparison between spiritual purgation and the log of wood which gradually becomes transformed through being immersed in fire and at last takes on the fire’s own properties. The force with which the familiar similitude is driven home impresses indelibly upon the mind and the fundamental concept of this most sublime of all purgations. Marvellous, indeed, are its effects, from the first enkindlings and burnings of Divine love, which are greater beyond comparison than those produced by the Night of Sense, the one being as different from the other as is the body from the soul. ‘For this (latter) is an enkindling of spiritual love in the soul, which, in the midst of these dark confines, feels itself to be keenly and sharply wounded in strong Divine love, and to have a certain realization and foretaste of God.’  No less wonderful are the effects of the powerful Divine illumination which from time to time enfolds the soul in the splendours of glory. When the effects of the light that wounds and yet illumines are combined with those of the enkindlement that melts the soul with its heart, the delights experience are so great as to be ineffable.
The second line of the first stanza of the poem is expounded in three admirable chapters (xi-xiii), while one short chapter (xiv) suffices for the three lines remaining. We then embark upon the second stanza, which describes the soul’s security in the Dark Night – due, among other reasons, to its being freed ‘not only from itself, but likewise from its other enemies, which are the world and the devil.' 
This contemplation is not only dark, but also secret (Chapter XVII), and in Chapter xviii is compared to the ‘staircase’ of the poem. This comparison suggests to the Saint an exposition (Chapters xviii, xix) of the ten steps or degrees of love which comprise St. Bernard’s mystical ladder. Chapter xxi describes the soul’s ‘disguise,’ from which the book passes on (Chapters xxii, xxiii) to extol the ‘happy chance’ which led it to journey ‘in darkness and concealment’ from its enemies, both without and within.
Chapter xxiv glosses the last line of the second stanza – ‘my house being now at rest.’ Both the higher and the lower ‘portions of the soul’ are now tranquillized and prepared for the desired union with the Spouse, a union which is the subject that the Saint proposed to treat in his commentary on the five remaining stanzas. As far as we know, this commentary was never written. We have only the briefest outline of what was to have been covered in the third, in which, following the same effective metaphor of night, the Saint describes the excellent properties of the spiritual night of infused contemplation, through which the soul journeys with no other guide or support, either outward or inward, than the Divine love ‘which burned in my heart.’
It is difficult to express adequately the sense of loss that one feels at the premature truncation of this eloquent treatise.  We have already given our opinion  upon the commentaries thought to have been written on the final stanzas of the ‘Dark Night.’ Did we possess them, they would explain the birth of the light – ‘dawn’s first breathings in the heav’ns above’ – which breaks through the black darkness of the Active and the Passive Nights; they would tell us, too, of the soul’s further progress towards the Sun’s full brightness. It is true, of course, that some part of this great gap is filled by St. John of the Cross himself in his other treatises, but it is small compensation for the incomplete state in which he left this edifice of such gigantic proportions that he should have given us other and smaller buildings of a somewhat similar kind. Admirable as are the Spiritual Canticle and the Living Flame of Love, they are not to completely knit into one whole as is this great double treatise. They lose both in flexibility and in substance through the closeness with which they follow the stanzas of which they are the exposition. In the Ascent and the Dark Night, on the other hand, we catch only the echoes of the poem, which are all but lost in the resonance of the philosopher’s voice and the eloquent tones of the preacher. Nor have the other treatises the learning and the authority of these. Nowhere else does the genius of St. John of the Cross for infusing philosophy into his mystical dissertations find such an outlet as here. Nowhere else, again, is he quite so appealingly human; for, though he is human even in his loftiest and sublimest passages, this intermingling of philosophy with mystical theology makes him seem particularly so. These treatises are a wonderful illustration of the theological truth that grace, far from destroying nature, ennobles and dignifies it, and of the agreement always found between the natural and the supernatural – between the principles of sound reason and the sublimest manifestations of Divine grace.
Manuscripts of the Dark Night
The autograph of the Dark Night, like that of the Ascent of Mount Carmel, is unknown to us: the second seems to have disappeared in the same period as the first. There are extant, however, as many as twelve early copies of the Dark Night, some of which, though none of them is as palaeographically accurate as the best copy of the Ascent, are very reliable; there is no trace in them of conscious adulteration of the original or of any kind of modification to fit the sense of any passage into a preconceived theory. We definitely prefer one of these copies to the others but we nowhere follow it so literally as to incorporate in our text its evident discrepancies from its original.
MS. 3,446, An early MS. in the clear masculine hand of an Andalusian: MS. 3,446 in the National Library, Madrid. Like many others, this MS. was transferred to the library from the Convento de San Hermengildo at the time of the religious persecutions in the early nineteenth century: it has been presented to the Archives of the Reform by the Fathers of Los Remedios, Seville -- a Carmelite house founded by P. Grecian in 1574. It has no title and a fragment from the Living Flame of Love is bound up with it.
This MS. has only two omissions of any length: these form part respectively of Book II, Chapters xix and xxiii. dealing with the Passive Night of the Spirit. It has many copyist's errors. At the same time, its antiquity and origin, and the good faith of which it shows continual signs, give it, in our view, primacy over the other copies now to come under consideration. It must be made dear, nevertheless, that there is no extant copy of the Dark Night as trustworthy and as skillfully made as the Alcaudete MS, of the Ascent.
MS. of the Carmelite Nuns of Toledo. Written in three hands, all early. Save for a few slips of the copyist, it agrees with the foregoing: a few of its errors have been corrected. It bears no title, but has a long sub-title which is in effect a partial summary of the argument.
MS. of the Carmelite Nuns of Valladolid. This famous convent, which was one of St. Teresa's foundations, is very rich in Teresan autographs, and has also a number of important documents relating to St. John of the Cross, together with some copies of his works. That here described is written in a large, clear hand and probably dates from the end of the sixteenth century. It has a title similar to that of the last-named copy. With few exceptions it follows the other most important MSS.
MS. Alba de Tormes. What has been said of this in the introduction to the Ascent (Image Books edition, pp. 6-7) applies also to the Dark Night. It is complete, save for small omissions on the part of the amanuensis, the 'Argument' at the beginning of the poem, the verses themselves and a few lines from Book II, Chapter vii.
MS. 6,624. This copy is almost identical with the foregoing. It omits the 'Argument' and the poem itself but not the lines from Book II, Chapter vii.
MS. 8,795. This contains the Dark Night, Spiritual Canticle, Living Flame of Love, a number of poems by St. John of the Cross and the Spiritual Colloquies between Christ and the soul His Bride. It is written in various hands, all very early and some feminine. A note by P. Andres de la Encarnacion, on the reverse of the first folio, records that the copy was presented to the Archives of the Reform by the Discalced Carmelite nuns of Baeza. This convent was founded in 1589, two years before the Saint's death, and the copy may well date from about this period. On the second folio comes the poem 'I entered in -- I knew not where.' On the reverse of the third folio begins a kind of preface to the Dark Night, opening with the words: 'Begin the stanzas by means of which a soul may occupy itself and become fervent in the love of God. It deals with the Dark Night and is divided into two books. The first treats of the purgation of sense, and the second of the spiritual purgation of man. It was written by P. Fr. Juan de la Cruz, Discalced Carmelite.' On the next folio, a so-called 'Preface: To the Reader' begins: 'As a beginning and an explanation of these two purgations of the Dark Night which are to be expounded hereafter, this chapter will show how narrow is the path that leads to eternal life and how completely detached and disencumbered must be those that are to enter thereby.' This fundamental idea is developed for hte space of two folios. There follows a sonnet on the Dark Night,  and immediately afterwards come the text of the treatise.
The copy contains many errors, but its only omission is that of the last chapter. There is no trace in it of any attempt to modify its original; indeed, the very nature and number of the copyist's errors are a testimony to his good faith.
MS. 12,658. A note by P. Andres states that he acquired it in Madrid but has no more detailed recollection of its provenance. 'The Dark Night,' it adds, 'begins on folio 43; our holy father is described simply as 'the second friar of the new Reformation,'  which is clear evidence of its antiquity.'
The Codex contains a number of opuscules, transcribed no doubt with a devotional aim by the copyist. Its epoch is probably the end of the sixteenth century; it is certainly earlier than the editions. There is no serious omission except that of six lines of the 'Argument.' The authors of the other works copied include St. Augustine, B. Juan de Avila, P. Baltasar Alvarez and P. Tomas de Jesus.
The copies which remain to be described are all mutilated or abbreviated and can be disposed of briefly:
MS. 13,498. This copy omits less of the Dark Night than of the Ascent but few pages are without their omissions. In one place a meticulous pair of scissors has removed the lower half of a folio on which the Saint deals with spiritual luxury.
MS. of the Carmelite Friars of Toledo. Dates from early in the seventeenth century and has numerous omissions, especially in the chapters on the Passive Night of the Spirit. The date is given (in the same hand as that which copies the title) as 1618. This MS. also contains an opuscule by Suso and another entitled 'Brief compendium of the most eminent Christian perfection of P. Fr. Juan de la Cruz.'
MS. 18,160. The copyist has treated the Dark Night little better than the Ascent; except from the first ten and the last three chapters, he omits freely.
MS. 12,411. Entitled by its copyist 'Spiritual Compendium,' this MS. contains several short works of devotion, including one by Ruysbroeck. Of St. John of the cross's works it copies the Spiritual Canticle as well as the Dark Night; the latter is headed: 'Song of one soul alone.' It also contains a number of poems, some of them by the Saint, and many passages from St. Teresa. It is in several hands, all of the seventeenth century. The copy of the Dark Night is most unsatisfactory; there are omissions and abbreviations everywhere.
MS. of the Carmelite Nuns of Pamplona. This MS. also omits and abbreviates continually, especially in the chapters on the Passive Night of Sense, which are reduced to a mere skeleton.
Editio princeps. This is much more faithful to its original in the Dark Night than in the Ascent. Both of the passages suppressed  and the interpolations  are relatively few and unimportant. Modifications of phraseology are more frequent and alterations are also made with the aim of correcting hyperbaton. In the first book about thirty lines are suppressed; in the second, about ninety. All changes which are of any importance have been shown in the notes.
The present edition. We have given preference, as a general rule, to MS. 3,446, subjecting it, however, to a rigorous comparison with the other copies. Mention has already been made in the introduction to the Ascent (Image Books edition, pp. lxiii-lxvi) of certain apparent anomalies and a certain lack of uniformity in the Saint's method of dividing his commentaries. This is nowhere more noticeable than in the Dark Night. Instead of dividing his treatise into books, each with its proper title, the Saint abandons this method and uses titles only occasionally. As this makes comprehension of his argument the more difficult, we have adopted the divisions which were introduced by P. Salablanca and have been copied by successive editors.
M. Baruzi (Bulletin Hispanique, 1922, Vol. xxiv. pp. 18-40) complains that this division weighs down the spiritual rhythm of the treatise and interrupts its movement. We do not agree. In any case, we greatly prefer the gain of clarity, even if the rhythm occasionally halts, to the other alternative -- the constant halting of the understanding. We have, of course, indicated every place where the title is taken from the editio princeps and was not the work of the author.
The following abbreviations are adopted in the footnotes:
A=MS. of the Discalced Carmelite Friars of Alba.
B=MS. 6,624 (National Library, Madrid).
Bz.=MS. 8,795 (N.L.M.)
C=MS. 13,498 (N.L.M.)
G=MS. 18,160 (N.L.M.)
H=MS. 3,446 (N.L.M.)
M=MS. of the Discalced Carmelite Nuns of Toledo.
P=MS. of the Discalced Carmelite Friars of Toledo.
V=MS. of the Discalced Carmelite Nuns of Valladolid.
E.p.=Editio princeps (1618).
MS. 12,411 and the MS. of the Discalced Carmelite nuns of Pamplona are cited without abbreviations.
Exposition of the stanzas describing the method followed by the soul in its journey upon the spiritual road to the attainment of the perfect union of love with God, to the extent that is possible in this life. Likewise are described the properties belonging to the soul that has attained to the said perfection, according as they are contained in the same stanzas.