The idea of the Godhead being born into a human form and taking on a human life to act as a guide, teacher and intermediary to the Supreme is one that arises in the Hindu tradition, but has also arisen in Christianity and other religions over time throughout the world. The Infinite, the Eternal, the All-Powerful that Arjuna has glimpsed in his vision-experience is simply too overwhelming and it tends to overpower the human being. What the special sense of the Avatar provides is the ability to relate, to interact with and to respond to a personal relationship that has developed and which brings with it a closeness, an intimacy and level of trust that is not possible in the relations between the human and the World-Spirit.
Sri Aurobindo describes three suggestions offered by the Gita that provide different aspects of the relation between the human and the personal Divine. As a result of the vision he has been shown, Arjuna recognizes the divinity in the friend, mentor and companion he has taken for granted until that time: “Now only he sees the universal Spirit in the individual frame, the Divine embodied in humanity, the transcendent Inhabitant of this symbol of Nature.” He has been blinded by the outer form of humanity, but now he sees the inner truth of the Divine personality.
The second suggestion represents a link by which the Divinity can be interacted with and understood by the human being. “The infinite presence in its unmitigated splendour would be too overwhelming for the separate littleness of the limited, individual and natural man. A link is needed by which he can see this universal Godhead in his own individual and natural being, close to him, not only omnipotently there to govern all he is by universal and immeasurable Power, but humanly figured to support and raise him to unity by an intimate individual relation.”
The third suggestion is the reassurance and support that the human form provides to the Divine Reality: “The truth that reassures, even when known, is grasped with difficulty behind the formidable and mighty aspect of all-destructive Time and an incalculable Will and a vast immeasurable inextricable working. But there is too the gracious mediating form of divine Narayana, the God who is close to man and in man, the Charioteer of the battle and the journey, with his four arms of helpful power, a humanised symbol of Godhead, not this million-armed universality.”
“It makes close, visible, living, seizable the vast spiritual joy in which for the inner spirit and life of man the universal workings behind all their stupendous circling, retrogression, progression sovereignly culminate, their marvellous and auspicious upshot. To this humanised embodied soul their end becomes here a union, a closeness, a constant companionship of man and God, man living in the world for God, God dwelling in man and turning to his own divine ends in him the enigmatic world-process.”
Sri Aurobindo, Essays on the Gita, Second Series, Part I, Chapter 11, The Vision of the World-Spirit–The Double Aspect, pp. 377-379