Lord Krishna was the avatar or the incarnation of the Supreme Being into the form of a human being whereas Arjuna typifies the ordinary man, faced with one of the most difficult problems which anyone could conceive - the killing of his own kinsman.

The whole dialogue is placed in the middle of the battlefield of Kurukshetra amidst the din and clamor of a fratricidal war. Arjuna's problem was a particular one related to his particular need.
 
Lord Krishna's answer is the whole of the Bhagavad Gita, and cuts at the root of the human problem - which is ignorance. Ignorance of the nature of our own selves, ignorance of the nature of the supreme Being and ignorance of the nature of the universe which we inhabit. This is the Srimad Bhagavad Gita.