What Brahman is cannot be described. All things in the world — the Vedas, the Puranas, the Tantras, the six systems of philosophy — have been defiled, like food that has been touched by the tongue, for they have been read or uttered by the tongue. Only one thing has not been defiled in this way, and that is Brahman. No one has ever been able to say what Brahman is.
Ramakrishna, Sayings of Sri Ramakrishna