Interaction of Maha Maya and Ahamkara (Illusion Vs. Egoism) takes place so intensely that the false concept of ‘first person –I or Mine’ often overshadows the Truth of Reality. Normal human beings are the major sufferers of this interaction and understandably so because of their vulnerability to defeats and successes happening at every step in life, resulting in sorrows and joys. Strangely enough however, Devas who are expected to be the repositories of equanimity often tend to be the victims of this conflict. Worse would be in the case of Trinity sometimes!
The conflict of Realism versus self-centeredness came to fore when Vishnu and Mahadeva began to claim supremacy over each other. Their inner awareness was overshadowed as they fought and tended to divide loyalties among Devas and the susceptible humans. The clash continued and they used to brag before their respective spouses who were quiet as they knew the Reality. As the collision took a serious turn, both Maha Lakshmi and Girija Devi left their respective abodes. Both Vishnu and Siva lost their controls and Shaktis.
As both realised their follies and prayed to Maha Bhagavati, She appeared along with spouses and warned them that indeed they were like the grain and shell and in both the cases they were the shells and the Devi incarnations were the respective grains.