There is no way to union with God without annihilating the memory as to all forms (i.e., items of knowledge). This union cannot be wrought without a complete separation of the memory from all forms that are not God. As we mentioned in the night of the intellect, God cannot be encompassed by any form or distinct knowledge…. Since the memory cannot at the same time be united with God and with forms and distinct knowledge, and since God has no form or image comprehensible to the memory, the memory is without form and without figure when united with God. Its imagination being lost in great forgetfulness without the remembrance of anything, it is absorbed in a supreme good. (Ascent of Mount Carmel–St John of the Cross).

An important understanding about deeper interior prayer is being conveyed here. Even though contemplation always has an element of passive receptivity to grace, as will be examined later more fully, it is nonetheless necessary that the faculties of the soul exercise a suitable effort of their own in denying and rejecting their inclination to seek easier satisfactions in prayer. These faculties play a key role by their own choice in accepting the purgative darkness that descends upon the faculty, particularly in a deeper prayer of contemplation. A spirit of surrender to effects that may be hard to manage, and difficult to understand at first as a benefit, is necessary for the contemplative path to God.

“Saint John of the Cross: Master of Contemplation” by Father Donald Haggerty

You do very well, O soul, to seek Him ever as one hidden, for you exalt God and approach very near Him when you consider Him higher and deeper than anything you can reach. Hence pay no attention, neither partially nor entirely, to anything your faculties can grasp. I mean that you should never seek satisfaction in what you understand about God, but in what you do not understand about Him. Never pause to love and delight in your understanding and experience of God, but love and delight in what you cannot understand or experience of Him. Such is the way, as we said, of seeking Him in faith. However surely it may seem that you find, experience, and understand God, because he is inaccessible and concealed you must always regard Him as hidden, and serve Him who is hidden in a secret way. –St John of the Cross ‘Spiritual Canticle’

St John of the Cross Adoring

Since, then, your beloved Bridegroom is the treasure hidden in a field for which the wise merchant sold all his possessions, and that field is your soul, in order to find Him you should forget all your possessions and all creatures and hide in the secret inner room of your spirit and there, closing the door behind you (your will to all things), you should pray to your Father in secret. Remaining hidden with Him, you will experience Him in hiding, that is, in a way transcending all language and feeling lives hidden within your heart, strive to be really hidden with Him, and you will embrace Him within you and experience Him with loving affection.  –St John of the Cross ‘Spiritual Canticle’