First part of Devī Māhātmya, consisting of first chapter only, invokes the Goddess as Mahākālī — the one, who resides at our root chakra and helps us transcend tamo guna, with all its fears that often paralyse our ability to move forward in life.
Our brain is comprised of three distinctive parts, each more evolved than the previous one. The most “primitive” part of our brain is often called reptile or lizard brain — which is just a different name for brain stem. It plays a vital role in our survival, as it is primarily responsible for certain mechanical activities within our body — such as regulating sleep, heart rate, breathing, movement and digestion — without us even being aware of it.
One big weakness of this part of our brain, though, is that it is not really capable to discern between reality and imagination — neither does it perceive any difference between things which happened in the past or are happening right now. It is because it is not directly processing the sensory information, but simply observes what other parts of our brain are processing at the moment. Due to that it cannot distinguish between real threat and imagined threat — and that can lead to various exaggerated reactions, as well as insecurities.
This is what happens when tamo guna or “mode of ignorance” takes over. It is illustrated in Devī Māhātmya in the first chapter, in which the two demons, Madhu and Kaiṭabhā, emerge from Lord Viṣṇu’s ears, when He is engrossed in His cosmic slumber. When the two demons start creating chaos in the yet uncreated universe, Lord Brahma invokes Devī in the form Mahākālī to wake up the Lord — for only when He is awake He can fight the two demons and retrieve the Vedas, the knowledge which they have stolen. Similarly, Goddess in this form helps us to symbolically wake up from our delusions and fantasies, and inspires us to stay more alert and “awake” on our spiritual path, so that we can prevent our inner demons from appearing from the darkness of unconscious mind.
The first chapter is traditionally recited and contemplated upon on the first day of Navaratri.