In this excerpt, the author of The Cloud of Unknowing instructs the practitioner that he must put a cloud of forgetting between himself and all created things. That is to say, during this type of prayer, no thought is welcomed or indulged. The author is describing apophatic prayer – what is sometimes conceptualized as "resting in God."
"If you wish to enter into this cloud, to be at home in it, and to take up the contemplative work of love as I urge you to, there is something else you must do. Just as the cloud of unknowing lies above you, between you and your God, so you must fashion a cloud of forgetting beneath you, between you and every created thing. The cloud of unknowing will perhaps leave you with the feeling that you are far from God. But no, if it is authentic, only the absence of a cloud of forgetting keeps you from him now. Every time I say "all creatures," I refer not only to every created thing but also to all their circumstances and activities. I make no exception. You are to concern yourself with no creature whether material or spiritual nor with their situation and doings whether good or ill. To put it briefly, during this work you must abandon them all beneath the cloud of forgetting.
For although at certain times and in certain circumstances it is necessary and useful to dwell on the particular situation and activity of people and things, during this work it is almost useless. Thinking and remembering are forms of spiritual understanding in which the eye of the spirit is opened and closed upon things as the eye of a marksman is on his target. But I tell you that everything you dwell upon during this work becomes an obstacle to union with God. For if your mind is cluttered with these concerns there is no room for him.
Yes, and with all due reverence, I go so far as to say that it is equally useless to think you can nourish your contemplative work by considering God's attributes, his kindness or his dignity; or by thinking about our Lady, the angels, or the saints; or about the joys of heaven, wonderful as these will be. I believe that this kind of activity is no longer any use to you. Of course, it is laudable to reflect upon God's kindness and to love and praise him for it; yet it is far better to let your mind rest in the awareness of him in his naked existence and to love and praise him for what he is in himself."
– The Cloud of Unknowing, Chapter 5