The medieval theologian and mystic Meister Eckhart may have been one of the most emphatic on in encouraging unknowing. 

He says that the place where God speaks, and works has less to do with right action, right emotion or right mindset and more to do with space. Eckhart calls this open space the “potential of receptivity.” He says that we create space through silence and stillness and await a birth within us. “There must be a silence and a stillness, and the Father must speak in that.” Eckhart affirms that this birth has nothing to do with good deeds or religious purity as we think of it but rather, it occurs in both sinners and saints – even those in hell.

Eckhart speaks of creating a space through the practice of silence and stillness that is absolute and is far more extreme than most Christian practices. It includes letting go of images, understanding, intellect, memory, sense perceptions, imagination and even ideas about God being good or compassionate.

Pope John XXII issued a bull (In agro dominico), 27 March 1329, in which a series of statements from Eckhart is characterized as heretical, another as suspected of heresy. Many today consider him to be one the great mystics.

Meister Eckhart. The Complete Mystical Works of Meister Eckhart with foreword by Bernard McGinn, trans. Maurice O’C Walshe. (New York: Crossroad Publishing, 2009