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.
There is a statement in the Brahma-saṁhitā: Just ride on the airplane which runs at the speed of mind. Our material airplanes can run two thousand miles per hour, but what is the speed of mind? You are sitting at home, you immediately think of India—say, ten thousand miles away—and at once it is in your home. Your mind has gone there. The mind-speed is so swift. Therefore it is stated, "If you travel at this speed for millions of years, you'll find that the spiritual sky is unlimited." It is not possible even to approach it. Therefore, the Vedic injunction is that one must approach—the word "compulsory" is used—a bona fide spiritual master, a guru. And what is the qualification of a spiritual master? He is one who has rightly heard the Vedic message from the right source. And he must practically be firmly established in Brahman. These are the two qualities he must have. Otherwise he is not bona fide.
This Kṛṣṇa consciousness movement is completely authorized from Vedic principles. In the Bhagavad-gītā Kṛṣṇa says, "The actual aim of Vedic research is to find out Kṛṣṇa." In the Brahma-saṁhitā it is also stated, "Kṛṣṇa, Govinda, has innumerable forms, but they are all one." They are not like our forms, which are fallible. His form is infallible. My form has a beginning, but His form has no beginning. It is ananta. And His form—so many multiforms—has no end. My form is sitting here and not in my apartment. You are sitting there and not in your apartment. But Kṛṣṇa can be everywhere at one time. He can sit down in Goloka Vṛndāvana, and at the same time He is everywhere, all-pervading. He is original, the oldest, but whenever you look at a picture of Kṛṣṇa you'll find a young boy fifteen or twenty years old. You will never find an old man. You have seen pictures of Kṛṣṇa as a charioteer from the Bhagavad-gītā. At that time He was not less than one hundred years old. He had great-grandchildren, but He looked just like a boy. Kṛṣṇa, God, never becomes old. That is His supreme power. And if you want to search out Kṛṣṇa by studying the Vedic literature, then you will be baffled. It may be possible, but it is very difficult. But you can very easily learn about Him from His devotee. His devotee can deliver Him to you: "Here He is, take Him." That is the potency of Kṛṣṇa's devotees.