After hearing Bhagavad-gītā from the Supreme Personality of Godhead, Arjuna accepted Kṛṣṇa as paraṁ brahma, the Supreme Brahman. Every living being is Brahman, but the supreme living being, or the Supreme Personality of Godhead, is the Supreme Brahman. Paraṁ dhāma means that He is the supreme rest or abode of everything; pavitram means that He is pure, untainted by material contamination; puruṣam means that He is the supreme enjoyer; śāśvatam, original; divyam, transcendental; ādi-devam, the Supreme Personality of Godhead; ajam, the unborn; and vibhum, the greatest.
Now one may think that because Kṛṣṇa was the friend of Arjuna, Arjuna was telling Him all this by way of flattery, but Arjuna, just to drive out this kind of doubt from the minds of the readers of Bhagavad-gītā, substantiates these praises in the next verse when he says that Kṛṣṇa is accepted as the Supreme Personality of Godhead not only by himself but by authorities like Nārada, Asita, Devala and Vyāsadeva. These are great personalities who distribute the Vedic knowledge as it is accepted by all ācāryas. Therefore Arjuna tells Kṛṣṇa that he accepts whatever He says to be completely perfect. Sarvam etad ṛtaṁ manye: "I accept everything You say to be true." Arjuna also says that the personality of the Lord is very difficult to understand and that He cannot be known even by the great demigods. This means that the Lord cannot even be known by personalities greater than human beings. So how can a human being understand Lord Śrī Kṛṣṇa without becoming His devotee?
Therefore Bhagavad-gītā should be taken up in a spirit of devotion. One should not think that he is equal to Kṛṣṇa, nor should he think that Kṛṣṇa is an ordinary personality or even a very great personality. Lord Śrī Kṛṣṇa is the Supreme Personality of Godhead. So according to the statements of Bhagavad-gītā or the statements of Arjuna, the person who is trying to understand the Bhagavad-gītā, we should at least theoretically accept Śrī Kṛṣṇa as the Supreme Personality of Godhead, and with that submissive spirit we can understand the Bhagavad-gītā. Unless one reads the Bhagavad-gītā in a submissive spirit, it is very difficult to understand Bhagavad-gītā, because it is a great mystery.
Just what is the Bhagavad-gītā? The purpose of Bhagavad-gītā is to deliver mankind from the nescience of material existence. Every man is in difficulty in so many ways, as Arjuna also was in difficulty in having to fight the Battle of Kurukṣetra. Arjuna surrendered unto Śrī Kṛṣṇa, and consequently this Bhagavad-gītā was spoken. Not only Arjuna, but every one of us is full of anxieties because of this material existence. Our very existence is in the atmosphere of nonexistence. Actually we are not meant to be threatened by nonexistence. Our existence is eternal. But somehow or other we are put into asat. Asat refers to that which does not exist.
Out of so many human beings who are suffering, there are a few who are actually inquiring about their position, as to what they are, why they are put into this awkward position and so on. Unless one is awakened to this position of questioning his suffering, unless he realizes that he doesn't want suffering but rather wants to make a solution to all suffering, then one is not to be considered a perfect human being. Humanity begins when this sort of inquiry is awakened in one's mind. In the Brahma-sūtra this inquiry is called brahma jijñāsā. Athāto brahma jijñāsā. Every activity of the human being is to be considered a failure unless he inquires about the nature of the Absolute. Therefore those who begin to question why they are suffering or where they came from and where they shall go after death are proper students for understanding Bhagavad-gītā. The sincere student should also have a firm respect for the Supreme Personality of Godhead. Such a student was Arjuna.
Lord Kṛṣṇa descends specifically to reestablish the real purpose of life when man forgets that purpose. Even then, out of many, many human beings who awaken, there may be one who actually enters the spirit of understanding his position, and for him this Bhagavad-gītā is spoken. Actually we are all swallowed by the tigress of nescience, but the Lord is very merciful upon living entities, especially human beings. To this end He spoke the Bhagavad-gītā, making His friend Arjuna His student.
Being an associate of Lord Kṛṣṇa, Arjuna was above all ignorance, but Arjuna was put into ignorance on the Battlefield of Kurukṣetra just to question Lord Kṛṣṇa about the problems of life so that the Lord could explain them for the benefit of future generations of human beings and chalk out the plan of life. Then man could act accordingly and perfect the mission of human life.
The subject of the Bhagavad-gītā entails the comprehension of five basic truths. First of all, the science of God is explained and then the constitutional position of the living entities, jīvas. There is īśvara, which means the controller, and there are jīvas, the living entities which are controlled. If a living entity says that he is not controlled but that he is free, then he is insane. The living being is controlled in every respect, at least in his conditioned life. So in the Bhagavad-gītā the subject matter deals with the īśvara, the supreme controller, and the jīvas, the controlled living entities. Prakṛti (material nature) and time (the duration of existence of the whole universe or the manifestation of material nature) and karma (activity) are also discussed. The cosmic manifestation is full of different activities. All living entities are engaged in different activities. From Bhagavad-gītā we must learn what God is, what the living entities are, what prakṛti is, what the cosmic manifestation is, how it is controlled by time, and what the activities of the living entities are.