The "Brihadaranyaka Upanishad" starts the second chapter as a conversation between Ajatashatru and "Balaki Gargya" on theory of dreams, positing that human beings see dreams entirely unto themselves because mind draws, in itself, the powers of sensory organs, which it releases in the waking state. It then asserts that this empirical fact about dreams suggests that human mind has the power to perceive the world as it is, as well as fabricate the world as it wants to perceive it. Mind is a means, prone to flaws. The struggle man faces, asserts Brihadaranyaka in brahmana 3, is in his attempt to realize the "true reality behind perceived reality". That is Atman-Brahman, inherently and blissfully existent, yet unknowable because it has no qualities, no characteristics, it is "neti, neti" (literally, "not this, not this").