But thou shalt ever seek with great diligence in prayer that thou mayest come to a spiritual feeling or sight of God. And that is, that thou mayest know the wisdom of God, the endless might of Him, His great goodness in Himself and in His creatures; for this is Contemplation, and that other mentioned is none, thus saith St Paul: Being rooted and grounded in charity, we may be able to comprehend with all the saints what is the breadth and length and height and depth. That ye may know, he saith not, by sound of the ear nor sweet savour in the mouth, nor by any such bodily thing, but that ye may know and feel with all saints what is the length of the endless being of God, the breadth of the wonderful charity and the goodness of God, the height of His almighty Majesty and the bottomless depths of His wisdom. In knowing and spiritual feeling of these should be the exercise of a Contemplative man. (John Climacus)

To feel and know God is to feel and know ultimate reality, the creator of the universe, the fundamental nature of being.

Compare John's late sixth century explanation of God to Einstein's mid-20th century discussion of faith:

A knowledge of the existence of something we cannot penetrate, of the manifestations of the profoundest reason and the most radiant beauty - it is this knowledge and this emotion that constitute the truly religious attitude; in this sense, and in this alone, I am a deeply religious man.

To mindfully approach our ultimate ground of being requires a radical openness, vulnerability, and willingness to experience what is beyond our specific understanding.

Yet this is the same creation and context on which we daily depend, continually experience, and presume to understand.