Source : http://www.thehindu.com/society/faith/staunch-devotion-the-key/article18475184.ece
Immediately after the revelation of His cosmic form, Krishna explains to Arjuna that only through unswerving devotion to Him can He be known and realised. “He who does work for Me, he who looks upon Me as his goal, he who worships Me free from attachment, who is free from enmity to all creatures, he goes to Me.”
Adi Sankara, in his commentary on the Gita, shows that this statement reflects the essence of the entire Gita teaching, pointed out Sri K. Ramasubramania Sarma in a discourse. It clearly teaches whatever one has to imbibe and practise in life, namely, that one who leads life with his mind fixed on God at all times and remains devoted to Him automatically reaches the goal.
The answer to Arjuna’s doubt regarding the relative merits of jnana and karma is provided here. The two paths are not mutually exclusive and intersect very often and only when being practised one realises this truth. Spiritual knowledge has nothing to do with theoretical or empirical learning or intellectual attainments. It is the direct and intuitive experience or vision of the Absolute Reality. For some it is felt as a moment of illumination in the inner recesses of one’s understanding which soon gets submerged in the rising waves of worldly experiences.
In the case of Arjuna, the vision of the cosmic form of the Lord confers an understanding of the grand design of creation in which all beings subsist in the cycle of birth, growth and death in a somewhat endless manner. But the Lord makes it clear that beholding the vision, which is itself a divine gift, is not attainment of the goal. This vision should help one to gain a permanent experience of the divine truth. Such an awareness that forms the backbone of one’s existence is possible only to one who has staunch devotion to the Lord.