What are the main themes, or motifs in this epic poem?
I think that one of the most critical themes to emerge from The Mahabharatais the need to maintain a sense of order of the world. Individuals are seen as part of something larger and must act accordingly. The work illuminates a resounding theme of interconnection. Whether is the discussion between Lord Krishna or Arjuna, or the fate of battles, or the resumption of the Pandava power, the work is concerned with ensuring that individuals recognize their part in a larger configuration. There is little in way of individual alienation. This theme is seen in how the work stresses that the individual has a sense of responsibility or dharma in what they do. Such a critical idea is evident when Lord Krishna advises Arjuna to take action in the maintenance of the social order. Individuals are compelled to believe that they are not alone, not isolated. In all of these instances, the underlying themes is that action in the name of dharma and responsibility is vitally important for the individual.
Another theme that is essential in the work is the clear construction of good and evil. In the Mahabharata, there is good and there is evil. The work develops these themes in suggesting that individual action moves the individual closer to one side or the other. Either one acts in accordance with the Pandava notion of the good or one follows the lineage of the blind king Dhritarashtra and his son in the opposite manner. The development of this theme helps to establish how individual action should be taken and how accordance with this order results in the restoration of "sight" of the good. Such themes become of vital importance to both the work and its place amongst epic literature.