Vedic knowledge is called śabda-pramāṇa. Another name is śruti. Śruti means that this knowledge has to be received simply by aural reception. The Vedas instruct that in order to understand transcendental knowledge, we have to hear from the authority. Transcendental knowledge is knowledge from beyond this universe. Within this universe is material knowledge, and beyond this universe is transcendental knowledge. We cannot even go to the end of the universe, so how can we go to the spiritual world? Thus to acquire full knowledge is impossible.
There is a spiritual sky. There is another nature, which is beyond manifestation and nonmanifestation. But how will you know that there is a sky where the planets and inhabitants are eternal? All this knowledge is there, but how will you make experiments? It is not possible. Therefore you have to take the assistance of the Vedas. This is called Vedic knowledge. In our Kṛṣṇa consciousness movement we are accepting knowledge from the highest authority, Kṛṣṇa. Kṛṣṇa is accepted as the highest authority by all classes of men. I am speaking first of the two classes of transcendentalists. One class of transcendentalists is called impersonalistic, Māyāvādī. They are generally known as Vedāntists, led by Śaṅkarācārya. And there is another class of transcendentalists, called Vaiṣṇavas, like Rāmānujācārya, Madhvācārya, Viṣṇu Svāmī. Both the Śaṅkara-sampradāya and the Vaiṣṇava-sampradāya have accepted Kṛṣṇa as the Supreme Personality of Godhead. Śaṅkarācārya is supposed to be an impersonalist who preached impersonalism, impersonal Brahman, but it is a fact that he is a covered personalist. In his commentary on the Bhagavad-gītā he wrote, "Nārāyaṇa, the Supreme Personality of Godhead, is beyond this cosmic manifestation." And then again he confirmed, "That Supreme Personality of Godhead, Nārāyaṇa, is Kṛṣṇa. He has come as the son of Devakī and Vasudeva." He particularly mentioned the names of His father and mother. So Kṛṣṇa is accepted as the Supreme Personality of Godhead by all transcendentalists. There is no doubt about it. Our source of knowledge in Kṛṣṇa consciousness is the Bhagavad-gītā, which comes directly from Kṛṣṇa. We have published Bhagavad-gītā As It Is because we accept Kṛṣṇa as He is speaking, without any interpretation. That is Vedic knowledge. Since the Vedic knowledge is pure, we accept it. Whatever Kṛṣṇa says, we accept. This is Kṛṣṇa consciousness. That saves much time. If you accept the right authority, or source of knowledge, then you save much time. For example, there are two systems of knowledge in the material world: inductive and deductive. From deductive, you accept that man is mortal. Your father says man is mortal, your sister says man is mortal, everyone says man is mortal—but you do not experiment. You accept it as a fact that man is mortal. If you want to research to find out whether man is mortal, you have to study each and every man, and you may come to think that there may be some man who is not dying but you have not seen him yet. So in this way your research will never be finished. In Sanskrit this process is called āroha, the ascending process. If you want to attain knowledge by any personal endeavor, by exercising your imperfect senses, you will never come to the right conclusions. That is not possible.