Srimad Bhagvad Gita

Bhagvad Gita is the divine song of the God. Its a commune between Lord Krishna and Arjuna just before the battle of Mahabharta started. Before start of battle Arjuna on seeing Bhishma and Dronacharya goes into depression because they are his elders and also stronger than him. So fighting with his loved ones and fear of failure led to the depression.