One having knowledge for his eye can say this much with the help of reason and analogy. Brahma which is indestructible can be comprehended by only withdrawing the senses and the mind.
हेतुमच्छक्यमाख्यातुमेतावज्ज्ञानचक्षुषा। प्रत्याहारेण वा शक्यमक्षरं ब्रह्म वेदितुम्॥