A terrible, unbearable mystery!

Alexander Men, who possessed an unique combination of broad erudition, openness to secular culture, science, to other confessions, to non-Christian religions, and deep Christian roots from the Catacomb Church 

(from "History of Religion" by Alexander Men):

Following the path blazed by contemplation, the Indian Brahmins come to the same conclusion as all mystics have come to, no matter what time and no matter what people they live in. Yajnavalkya and Buddha, Plotinus and the Areopagite, Meister Eckhart and Gregory Palamas, the Kabbalists and Nicholas of Cusa, Jacob Boehme, Ruysbroek and many other clairvoyants of East and West, with a unanimity that involuntarily awes, proclaim what they have known, having reached the very limits of life. 

All of them, as one, testify that everything conceivable and imaginable disappears There, that there is nothing There, and at the same time - the inexpressible Fullness. It is impossible to find There any of the properties of the world, nature and spirit; There is neither good nor evil, neither light nor darkness, neither movement nor rest. There reigns something that transcends the deepest thought of man, transcends Being itself. In the sacred darkness that hides the basis of the foundations, they felt the reality of the Existing, the Absolute. A terrible, unbearable mystery!...