The ultimate revelation
All the previous aspects of the Lord are still connected with the material nature. Turīya, however is the Lord Himself, fully transcendental and immersed in transcendental bliss.
« The Muṇḍaka Upaniṣad: An in-depth study
The Fourth Khaṇḍa
The material creation is a perverted reflection of the original reality, just as a tree reflected on a lake. In contact with this reflection, our propensity of love for Krsna is manifested as the desire to enjoy matter, which is the cause of our whole conditioned existence. Beyond the darkness of our struggle for existence in this material world is the transcendental abode of the Lord, where He performs pastimes with His eternal associates. This eternal abode can't be understood by mental speculation, but it can be achieved through transcendental knowledge received from a liberated soul and proper devotional practice.
The ultimate revelation
All the previous aspects of the Lord are still connected with the material nature. Turīya, however is the Lord Himself, fully transcendental and immersed in transcendental bliss. One who comes to know this Supreme Lord transcends all aspects of material existence and returns to his original spiritual consciousness, fully blissful and free from duality.
Turīya is the nāda or silence in the Omkāra, as well as the complete syllable. He is beyond sense perception and intellect. He can be understood only through pure devotional service. The empiric methods that can be used to understand the previous aspects are ineffective.
Text 4.1
amātraś caturtho'vyavahāryaḥ prapañcopaśamaḥ śivo'dvaitaḥ
evam onkāra ātmā eva
samviśaty ātmānam ātmanā ya evam veda
The unlimited and indivisible fourth is beyond sensory experience, beyond actions and interactions. He brings the cessation of all material phenomena. He is beyond material duality, the destroyer of false knowledge, and fully blissful. This Omkāra is indeed the Supreme Self. One who knows this attains the Supreme Self, entering into the spiritual nature by His grace.
Commentary: Amātrah means without measure, unlimited. Although the material universe we live in is extremely large by our calculation, it is just one of millions and billions of material universes floating on the causal ocean, and one of the smallest of them. All the universes combined form just one-quarter of Krsna's potency and the other three-quarters correspond to the planets of the spiritual sky. This point is described in more detail by Srila Prabhupada in the 9th chapter of Teachings of Lord Caitanya:
"From revealed scriptures it is understood that Kṛṣṇa lives in three transcendental places. The most confidential residence of Kṛṣṇa is Goloka Vṛndāvana. It is there that He stays with His father, mother and friends, exhibits His transcendental relationships and bestows His mercy amongst His eternal entourage. There yogamāyā acts as His maidservant in the rāsa-līlā dance. The residents of Vrajabhūmi think, "The Lord is glorified by particles of His transcendental mercy and affection, and we, the residents of Vṛndāvana, have not the slightest anxiety due to His merciful existence." As stated in Brahma-samhitā (5.43), all the Vaikuṇṭha planets in the spiritual sky (known as Viṣṇuloka) are situated in the planet known as Kṛṣṇaloka, Goloka Vṛndāvana. In that supreme planet the Lord enjoys His transcendental bliss in multiple forms, and all the opulences of the Vaikuṇṭhas are fully displayed in that one planet. The associates of Kṛṣṇa are also full with six opulences. In the Pādmottara-khaṇḍa (225.57) it is stated that the material energy and the spiritual energy are separated by water known as the Virajā River. That river flows from the perspiration of the first puruṣa incarnation. On one bank of the Virajā is the eternal nature, unlimited and all-blissful, called the spiritual sky, and this is the spiritual kingdom, or the kingdom of God. The spiritual planets are called Vaikuṇṭhas because there is no lamentation or fear there; everything is eternal. The spiritual world has been calculated to comprise three-fourths of the energies of the Supreme Lord, and the material world is said to comprise one-fourth of His energy, but no one can understand what this three-fourths is, since even this material universe, which comprises only one-fourth of His energy, cannot be described. Trying to convey to Sanātana Gosvāmī something of the extent of one-fourth of Kṛṣṇa's energy, Caitanya Mahāprabhu cited an incident from Śrīmad-Bhāgavatam in which Brahmā, the lord of the universe, came to see Kṛṣṇa at Dvārakā. When Brahmā approached Kṛṣṇa, the doorman informed Kṛṣṇa that Brahmā had arrived to see Him. Upon hearing this, Kṛṣṇa inquired as to which Brahmā had come, and the doorman returned to Brahmā and asked, "Which Brahmā are you? Kṛṣṇa has asked."
Brahmā was struck with wonder. Why did Kṛṣṇa ask such a question? He informed the doorman, "Please tell Him that Brahmā, who is the father of the four Kumāras and who has four heads, has come to see Him."
The doorman informed Kṛṣṇa and then asked Brahmā inside. Brahmā offered his obeisances unto the lotus feet of Kṛṣṇa, and after receiving him with all honor, Kṛṣṇa inquired about the purpose of his visit.
"I shall tell You of my purpose in coming here," Lord Brahmā replied, "but first I have a doubt which I ask You to kindly remove. Your doorman told me that You asked which Brahmā has come to see You. May I inquire if there are other Brahmās besides me?"
Upon hearing this, Kṛṣṇa smiled and at once called for many Brahmās from many universes. The four-headed Brahmā then saw many other Brahmās coming to see Kṛṣṇa and to offer their respects. Some of them had ten heads, some had twenty, some had a hundred and some even had a million heads. Indeed, the four-headed Brahmā could not even count the Brahmās who were coming to offer their obeisances to Kṛṣṇa. Kṛṣṇa then called many other demigods from various universes, and they all came to offer their respects to the Lord. Upon seeing this wonderful exhibition, the four-headed Brahmā became nervous and began to think of himself as no more than a mosquito in the midst of many elephants. Since so many demigods were offering obeisances unto the lotus feet of Kṛṣṇa, Brahmā concluded that the unlimited potency of Kṛṣṇa could not be estimated. All the helmets of the various demigods and Brahmās shone brightly in the great assembly, and the prayers of the demigods made a great sound.
"Dear Lord," the demigods said, "it is Your great mercy that You have called us to see You. Is there any particular order? If so, we will carry it out at once."
"There is nothing especially required of you," Lord Kṛṣṇa replied. "I only wanted to see you together at one time. I offer My blessing to you. Don't fear the demons."
"By Your mercy, everything is all right," they all replied. "There are no disturbances at present, for by Your incarnation everything inauspicious is vanquished."
As each of the Brahmās saw Kṛṣṇa, each thought that He was only within his universe. After this incident, Kṛṣṇa wished all the Brahmās farewell, and after offering respects to Him, they returned to their respective universes. Upon seeing this, the four-headed Brahmā at once fell down at the feet of Kṛṣṇa and said, "What I thought about You at first was all nonsensical. Everyone may say that they know You in perfection, but as far as I am concerned, I cannot begin to conceive how great You are. You are beyond my conception and understanding."
"This particular universe is only four thousand million miles broad," Kṛṣṇa then informed him, "but there are many millions and billions of universes which are far, far greater than this one. Some of these are many trillions of miles broad, and all these universes require strong Brahmās, not just four-headed." Kṛṣṇa further informed Brahmā, "This material creation is only a quarter manifestation of My creative potency. Three quarters of My creative potency is in the spiritual kingdom."
Avyavaharyah means beyond wordy experience. Everything we experience in the conditioned state of existence is experienced through material senses, gross or subtle. The Lord is however fully transcendental, beyond the experience of these material senses or material intelligence. He can be experienced only by pure souls who have revived their original spiritual senses through their practice of devotional service.
Prapañcopaśamaḥ means the cessation of prapañcha (the material existence, which expands from the five elements). One who attains the Supreme Lord finds the cessation of material existence and becomes Śiva (blissful) and advaita (free from duality and false knowledge).
Lord Turīya is designated by the nāda (the silence) in the Omkāra as well as the syllable as a whole. Because Turīya is beyond sense perception and beyond the limits of the material intellect, most of the descriptions offered are negative (He is beyond sound, beyond perception, beyond measure, etc.). In fact, He can be understood only through pure devotional service, which is indicated by the words ātmānam ātmanā (one can understand this Supreme Self only by the grace of the Lord Himself). The empiric methods used to understand Viśva, Taijasa, and Prājña are ineffective in understanding Turīya. He can be understood only by pure devotional service.
The Upaniṣads don't speak about devotional service as directly in the Srimad Bhagavatam and other Purāṇas, but still, the message is clear when we can properly understand the context and the conclusions of the text.
When we come to the conclusion of devotional service, a deeper meaning of the verse becomes possible:
This Supreme Lord, the Fourth is without measure and beyond the perception of the senses (amātraś caturtho). He is not perceivable to conditioned souls but becomes perceptible to pure devotees who are completely pure (avyavahāryaḥ). These pure devotees who surrender to the loving service of the Lord become just like the Lord, becoming the destroyer of all bodily bounds (prapañcopaśamaḥ), and thus capable of liberating others. They become spiritually blissful (Śiva) and situated in conclusive spiritual knowledge (advaitaḥ). The Lord is the Omkāra, and one who knows Him in truth, abandoning the false notion of being the body, attain the Supreme state of turīya by the mercy of the Lord Himself.
Just as in the previous aspects, one who worships the Supreme Lord as Turīya acquires qualities similar to Him. As Viśva, Taijasa, and Prājña the Lord is connected to the affairs of the material world (CC Ādi 2.52), and therefore the worshiper acquires different sorts of mystic powers. By worshiping the Supreme Lord through the process of devotional service, however, one becomes fully transcendental.