According to the Muktikā Upaniṣad, there are 108 Upaniṣads. Among these are the (1) Īśa, (2) Kena, (3) Kaṭha, (4) Praśna, (5) Muṇḍaka, (6) Māṇḍūkya, (7) Taittirīya, (8) Aitareya, (9) Chāndogya, (10) Bṛhad-āraṇyaka, (11) Brahma, (12) Kaivalya, (13) Jābāla, (14) Śvetāśvatara, (15) Haṁsa, (16) Āruṇeya, (17) Garbha and (18) Nārāyaṇa Upaniṣad. The 108 Upaniṣads contain all knowledge about the Absolute Truth. Sometimes people ask why Vaiṣṇavas use 108 prayer beads for chanting the holy names. We think it is because there are 108 Upaniṣads containing full knowledge of the Absolute Truth. On the other hand, some Vaiṣṇava transcendentalists think that the 108 beads represent the 108 companions of Lord Kṛṣṇa in His rāsa dance.
Lord Caitanya protested against misinterpretations of the Upaniṣads, rejecting any explanation which did not give their direct meaning. The direct interpretation is called abhidhā-vṛtti, whereas the indirect interpretation is called lakṣaṇā-vṛtti. The indirect interpretation serves no purpose. There are four kinds of understanding: (1) direct understanding (pratyakṣa), (2) hypothetical understanding (anumāna), (3) historical understanding (aitihya) and (4) understanding through sound (śabda). Of these four, understanding from the Vedic scriptures, the sound representations of the Absolute Truth, is the best method. Traditional Vedic students accept understanding through sound to be the best.
The stool and bone of any living entity are considered to be impure according to the Vedic literature, yet the same Vedic literature asserts that cow dung and conch shells are very pure. Apparently these statements are contradictory, but because cow dung and conch shells are considered pure by the Vedas, they are accepted as pure by the followers of the Vedas, without argument. If we try to understand the statements by indirect interpretation, creating some hypothesis, then we challenge the evidential authority of the Vedic statements. In other words, Vedic statements cannot be accepted according to our imperfect interpretations; they must be accepted as they are. If they are not accepted in this way, there is no authority in the Vedic statements.
According to Lord Caitanya, those who try to give some personal interpretation to Vedic statements are not at all intelligent. They mislead their followers by inventing their own interpretations. In India there is a class of men known as Ārya-samājists, who say that they accept the original Vedas only and reject all other Vedic literature. The motive of these people, however, is to give their own interpretation. According to Lord Caitanya, such interpretations are not to be accepted. They are simply not Vedic. Lord Caitanya said that the Vedic statements of the Upaniṣads are like sunlight. Everything is clear and very distinct when it is seen in the sunlight; the statements of the Vedas are similarly clear and distinct. The Māyāvādī philosophers simply cover the sunlight with the cloud of their misinterpretation.
Lord Caitanya then said that all the Vedic statements of the Upaniṣads aim at the ultimate truth, known as Brahman. The word Brahman means "the greatest," and "the greatest" should immediately be understood to refer to the Supreme Personality of Godhead, the source of all emanations. Unless the greatest possesses six opulences in full, he cannot be called the greatest. The greatest is therefore the Supreme Personality of Godhead. In other words, the Supreme Brahman is the Supreme Personality of Godhead. In the Bhagavad-gītā (10.12), the Supreme Personality of Godhead, Kṛṣṇa, is accepted by Arjuna as the Supreme Brahman. The conceptions of the impersonal Brahman and the localized Supersoul are contained within the understanding of the Supreme Personality of Godhead.