Mahabharata 3.202.12

3.202.12

yathāsvaṃ grāhakānyeṣāṃ śabdādīnāmimāni tu |
indriyāṇi yadā dehī dhārayanniha tapyate || 12 ||

Whatever is perceptible by the senses, is called vyakta (knowable or comprehensible) and whatever is beyond the reach of the senses and can only be perceived by guesses, is known to be avyakta (not vyakta). When a per on engages in the discipline of self-examination, after having subdued the senses which have of their own proper objective play in the external conditions of sound, form, &c, then he beholds his own spirit pervading the universe, and the universe reflected in itself. He who is wedded to his previous karma, although skilled in the highest spiritual wisdom, is cognisant only of his soul's objective existence, but the person whose soul is never affected by the objective conditions around, is never subject to ills, owing to its absorption in the elementary spirit of Brahma. When a person has overcome the domination of illusion, his manly virtues consisting of the essence of spiritual wisdom, turn to the spiritual enlightenment which illumines the intelligence of sentient beings. Such a person is styled by the omnipotent, intelligent Spirit as one who is without beginning and without end, self-existent, immutable, incorporeal and incomparable. This, O Brahmana, that thou hast enquired of me is only the result of self discipline. And this self-discipline can only be acquired by subduing the senses. It cannot be otherwise, heaven and hell are both dependent on our senses. When subdued, they lead to heaven; when indulged in, they lead to perdition.