'Spiritual Canticle' St. John of the Cross, Ed.&translated by E.A.Peers, Image Book edition, 1961. Part I

Stanza the first
Whither hast thou hidden thyself, And hast left me, O Beloved, to my sighing?

Exposition
In this first stanza, the soul that is enamored of the Word, the Son of God, her Spouse, desiring to be united with Him through clear and essential vision, sets forth her love's anxieties, reproaching Him for His absence, the more so because, being wounded by her love, for which she has abandoned all things, yea even herself, she has still to suffer the absence of her Beloved and is not yet loosed from her mortal flesh that she may be able to have fruition of Him in the glory of eternity. And thus she says: WHITHER HAST THOU HIDDEN THYSELF?
It is as thou she said: O Word, my Spouse, show me the place where thou art hidden. Wherein she begs Him to manifest His Divine Essence, the which is removed and hidden from every mortal eye and from all understanding. This Isaias signified when he said:"Verily Thou art a hidden God" (Isa XIV, 15). Here it is to be noted that, however lofty are the revelations of His presence, and however high and exalted is its knowledge of Him, they are not God in His Essence...For which cause says the prophet Job: "If He (that is to say God) comes to me, I shall not see Him: If He departs, I shall not understand Him (Job IX, 11). Wherein is to be understood that, if the soul should experience any great communications or knowledge of God, or any other feeling, it must not for that reason persuade itself that it possess God more completely or is more deeply in God; nor that that which it feels and understands Is God in His Essence, however profound that experience might be; and, if all these communications fail, it must not think that that for that reason God is failing it. For in reality the one estate can give no assurance to a soul that it is in His Grace, neither can the other, that it is outside it. As the Wise man says: No mortal man can know if he be worthy of the grace or of the hatred of God. So that the intent of the soul in this present line is not merely to beg for sensible and affective devotion, wherein there is neither certainty nor clear evidence of the possession of the Spouse in this life by grace, but also to beg for the presence and clear vision of His Essence, wherewith it desires to be given assurance and satisfaction in glory.
4.And it is to be observed, if one would learn how to find this Spouse (so far as may be in this life), that the Word, together with the father and the Holy Spirit, is hidden essentially in the inmost centre of the soul. Wherefore the soul that would find Him through union of love must go forth and hide itself from all created things according to the will, and enter within itself in deepest recollection, communing there with God in loving and affectionate fellowship, esteeming all that is in the world as though it were not. Hence Saint Augustine, speaking with God in the "Soliloquies" said: "I found Thee not, O Lord without, because I erred in seeking Thee without that wert within. He is then, hidden within the soul, and there the good contemplative must seek Him, saying:"whither hast Thou hidden Thyself?"
AND HAST LEFT ME, O BELOVED, TO MY SIGHTING?
5. The Bride calls Him 'Beloved' in order the more to move and incline Him to her prayer, for, when God is loved indeed, He hears the prayers of His lover with great readiness; and then in truth He can be called Beloved when the soul is wholly with Him and has not its heart set on aught that is outside Him. Some call the Spouse "Beloved' when He is not in truth their Beloved, because they have not their heart wholly with Him; and thus, before the Spouse, their petition is of less effect.
6. And in the words which she then says: 'And hast left me to my sighting' it is to be observe that the absence of the Beloved is a continual sighing in the heart of the lover, because apart from Him she loves naught, rests in naught and finds relief in naught; whence a man will know by this if he have indeed love toward God-namely, if he be content with aught that is less than God. To this sighting Saint Paul referred clearly when he said: We groan within ourselves, waiting for the adoption and possession of sons of God. Which is as though he said:Within our heart, where we have the pledge, we feel that which afflicts us- the absence. This, then, is sighing which the soul ever makes, for sorrow at the absence of her Beloved, above all when, having enjoyed some some kind of sweet and delectable communion with Him, she is left dry and alone. For this cause she grieves greatly, and says next:.......


In the "Cloud of unknowing" by anonymous English medieval mystic (translation by C. Wolters), 1961 ed. we read in chapter 6:

But now you will ask me, "How am I to think of God Himself, and what is He? And I cannot answer you except to say 'I do not know!'. For with this question you have brought me into the same darkness, the same cloud of unknowing where I want you to be! For though we through the grace of God can know fully about all other matters, and think about them-yes, even the very works of God Himself-yet of God Himself can no man think. Therefore I will leave on one side everything I can think, and choose for my love that thing which I cannot think! Why? BECAUSE HE MAY WELL BE LOVED, BUT NOT THOUGHT. BY LOVE HE CAN BE CAUGHT AND HELD, BUT BY THINKING NEVER. Therefore, though it may be good sometimes to think particularly about God's kindness and worth, and though it may be enlightening too, and a part of contemplation, yet in the work now before us it must be put down and covered with the cloud of forgetting. And you are to step over it resolutely and eagerly, with a devout and kindling love, and try to penetrate that darkness above you. Strike that thick cloud of unknowing (which is between God and you) with the deep dart of longing love, and on no account whatever think of giving up.
In chapter 16 (ibidem) we read: No one need think he presumes because he, the most wretched sinner in the world, now dares, after true amendment and a subsequent call to contemplation, and with the full support of his director and his conscience, to offer God his humble love, and secretly to press into that cloud of unknowing between him and God . For Our Lord said to Mary Magdalene, the typical representative of sinner called to contemplative life, "Thy sins are forgiven thee" (Luke 7:47). Not for her great sorrow; not for her anxiety over her sins; not for her humility as she contemplated her wretchedness; but surely, because she loved much. This is the point where we can see what secret and urgent love may obtain from Our Lord; far beyond anything we could imagine..... We need not be surprised; it is characteristic of the true lover that the more he loves, the more he wants to love.