"Meister Eckhart's mature understanding of letting-go-ness was comprehensive. Not only must the sinner let go of the world and sin, but also of all the traditional remedies proposed by the Church: pious acts of devotion and petitionary prayer aimed at flawed human notions of "God." The seeker had to let go of all images, desires, and thought itself. Only then was he or she ready for the final step in Eckhart's way to God, which is to be silent and let God work and speak within. Typically, the seeker was more aware of God...in a quiet places, but that requirement, Eckhart clarified, reflected human imperfection more than divine nature, for God is equally in all things and places. Most importantly, he continued,
all your activity must cease and all your powers must serve [God's] ends, not your own...No creaturely skill, nor your own wisdom nor all your knowledge can enable you to know God divinely. For you to know God in God's way, your knowing must become a pure unknowing, and a forgetting of yourself and all creatures. Now you might say, 'Well, sire, what use is my intellect then, if it is supposed to be empty and functionless? Is that the best thing for me to do – to raise my mind to an unknowing knowledge that can't really exist? For if I knew anything at all it would not be ignorance, and I should not be empty and bare. Am I supposed to be in total darkness?' Certainly. You cannot do better than to place yourself in darkness and in unknowing."
– Joel Harrington, Dangerous Mystic (italicized words are direct quotes from Eckhart's sermons)
The similarity of Eckhart's thought to The Cloud of Unknowing here is obvious.