APOPHATIC THEOLOGY AND ADVAITA VEDANTA

In the words of the 9^th-century theologian John Scotus Erigena: “We do not know what God is.  God Himself does not know what He is because He is not anything,” (i.e. not any created thing.) Literally God is not, because he transcends being.  

When he says “He is not anything” and “God is not,” Scotus does not mean that there is no God, but that God cannot be said to exist in the way that creation exists; God is uncreated. He is using apophatic language to emphasize that God is “other.” 

In Advaita Vedanta, Brahman is defined, apophatically, as nirguna or without qualities.  Anything imaginable or conceivable is not deemed to be the ultimate reality.  A Hindu hymn speaks of Brahman as "one where the mind does not reach."  In the Upanishads, Brahman is described as "neti-neti" or "neither this, nor that."

In the Mandukya Upanishad, verse 7, the Atman, the personal aspect of Brahman, is said, in a similar way, to be "not inwardly cognitive, not outwardly cognitive, not both-wise cognitive, not a cognition-mass, not cognitive, not non-cognitive, unseen, with which there can be no dealing, ungraspable, having no distinctive mark, non-thinkable, that which cannot be designated.” 

The apophatic approach is found extensively in Buddhist philosophy, as well.