Why does Lalitha Devi sit on Shiva?
Lalitha Sahasra Nama is the best answer for all your questions here. She is Shrichakra Raja nilaya- Lalitha Devi, the divine mother. Let me give the answers based on the picture above.
- Sachaamara Rama Vaani Savya Dakshina sevitha.
Rama (Lakshmi) and Vaani (Saraswathi) are said to do her seva with chamara (fans).
- sashara chaapa paasha ankushaam
The two weapons in her upper right and left hands are to cut the worldly desires in out heart and bring us to her feet. The weapon in the lower right hand is the ankusha which is used to poke us and remind us to come back to her feet, like a mahout pokes the elephant and teaches it discipline. The sugarcane in her lower left hand is not exactly a sugar can but is a bow made of sugar cane. This was manmadha's bow before he died. The bow is made of sugarcane, its string from bees and the arrows made from flowers (pushpa baana) used to shoot at people to make them fall in love to continue the population. After manmadha's death, mother took it into her hands and became Shri Kameshwari.
- Pancha Brahma asana sthitha (or) Pancha Prethasanaseena Pancha Brahma Swaroopini
The 5 brahmas sitting at her feet are actually the legs of her throne and these 5 brahmas are Brahma, Vishnu, Rudra, Ishwara and Sadashiva. These five become motionless without Shakti(her).
- Kumara Gana naadha Amba
The two sitting at her feet in the front are her sons Kumara and Ganesha.
- Shri Shivaa Shiva Shakti Aikya Rupini Lalithambika.
She is not exactly sitting on Him but it represents that she is Shivaa- the female or the energy of Shiva. Both are complete only when both are together and thus she forms Lalithambika.
That Chakra is our heart in a logical sense (I heard that our heart has the same number of grooves as the Chakra Raja has and the dot in the center is the divine mother). She sits in our heart and rules us and always takes care of us and takes us into her at the end.
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