Arjuna was in difficulty because of having to fight the battle of Kuruksetra. Arjuna surrendered to Krishna and consequently the Bhagavad Gita was spoken.
Not only Arjuna, but every one of us is full of anxieties because of this material existence. We are trying to exist here in the material world but the atmosphere of the material world is nonexistence. Actually we are not meant to be threatened by nonexistence. Our existence is eternal. But somehow or other we have been put into this temporary material world and because of this we are threatened with nonexistence.
Out of so many human beings who are suffering, there are only a few who are actually enquiring about their position, questioning what they are, why they are put into this difficult position, and so on. Unless one comes to this point of questioning his suffering, unless he realizes that he does not want to suffer, but rather he wants to find a solution to the suffering, then he can not be considered a perfect human being. Human life begins when this sort of enquiry is awakened in one’s mind.
Those who have come to this awakened position of questioning why they are suffering and who have realized they do not want to suffer, they want a solution to the suffering, are the proper students for understanding Bhagavad Gita. To be successful the sincere student should also have a firm respect for the Supreme Personality of Godhead. Arjuna is the perfect example of such a qualified student of the Bhagavad Gita.
The reason Krishna comes to the material world is specifically to re-establish the real purpose of life when mankind in general has forgotten this purpose. Krishna is very merciful to us, it is out of His mercy that He spoke the Bhagavad-gita, making His friend Arjuna the first student.
As Arjuna was an associate of Krishna he was above all ignorance. But just so Krishna could speak the Bhagavad Gita to him Krishna put Arjuna into ignorance on the battlefield of Kurukshetra so that he would question the Lord about the problems of life so Krishna could answer these questions and explain everything for the benefit of future generations of human beings. With this knowledge given by Krishna to Arjuna on the battlefield men can act accordingly and perfect their mission of human life.